Guidelines for the management of tracheal intubation in critically ill adults

These guidelines describe a comprehensive strategy to optimize oxygenation, airway management, and tracheal intubation in critically ill patients, in all hospital locations. They are a direct response to the 4^th National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society, which highlighted deficient management of these extremely vulnerable patients leading to major complications and avoidable deaths. They are founded on robust evidence where available, supplemented by expert consensus opinion where it is not. These guidelines recognize that improved outcomes of emergency airway management require closer attention to human factors, rather than simply introduction of new devices or improved technical proficiency. They stress the role of the airway team, a shared mental model, planning, and communication throughout airway management. The primacy of oxygenation including pre- and peroxygenation is emphasized. A modified rapid sequence approach is recommended. Optimal management is presented in an algorithm that combines Plans B and C, incorporating elements of the Vortex approach. To avoid delays and task fixation, the importance of limiting procedural attempts, promptly recognizing failure, and transitioning to the next algorithm step are emphasized. The guidelines recommend early use of a videolaryngoscope, with a screen visible to all, and second generation supraglottic airways for airway rescue. Recommendations for emergency front of neck airway are for a scalpel-bougie-tube technique while acknowledging the value of other techniques performed by trained experts. As most critical care airway catastrophes occur after intubation, from dislodged or blocked tubes, essential methods to avoid these complications are also emphasized.

Advanced care planning in care homes for older people: a qualitative study of the views of care staff and families

OBJECTIVE

to explore views on advance care planning in care homes for older people.

DESIGN

qualitative exploration of views from care home staff and the family of residents in care homes for older people.

SETTING

all care homes for the elderly in two London Boroughs.

PARTICIPANTS

staff (care managers, nurses and care assistants), community nurses and families.

METHODS

individual semi-structured interviews.

RESULTS

themes of the analysis: (i)

BENEFITS

staff and family revealed positive opinions towards advance care planning. Staff felt it provided choice for residents and encouraged better planning. (ii) Barriers: staff and families perceived residents as reluctant to discuss advance care planning. Some care assistants were reluctant to be involved. Furthermore, families and staff reported prevalence of dementia among residents as another barrier. Nurses and care managers identified both family involvement and unforeseen medical circumstances as problematic. (iii) Facilitators: (a) early initiation of discussions (b) family involvement to establish preferences (c) residents and staff being well-known to each other and (d) staff training, were perceived to facilitate ACP.

CONCLUSIONS

overall, staff and families support the concept of ACP. Methods to overcome the identified barriers are required to embed ACP within end of life care in care homes.

Rskalpha-actin/hIGF-1 transgenic mice with increased IGF-I in skeletal muscle and blood: impact on regeneration, denervation and muscular dystrophy

Human IGF-I was over-expressed in skeletal muscles of C57/BL6xCBA mice under the control of the rat skeletal alpha-actin gene promoter. RT-PCR verified expression of the transgene in skeletal muscle but not in the liver of 1- and 21-day old heterozygote transgenic mice. The concentration of endogenous mouse IGF-I, measured by an immunoassay which does not detect human IGF-I, was not significantly different between transgenic mice and wild-type littermates (9.5 +/- 0.8 and 13.3 +/- 1.9 ng/g in muscle; 158.3 +/- 18.6 and 132.9 +/- 33.1 ng/ml in plasma, respectively). In contrast, quantitation with antibodies to human IGF-I showed an increase in IGF-I of about 100 ng/ml in plasma and 150 ng/g in muscle of transgenic mice at 6 months of age. Transgenic males, compared to their age matched wild-type littermates, had a significantly higher body weight (38.6 +/- 0.53 g vs. 35.8 +/- 0.64 g at 6 months of age; P < 0.001), dry fat-free carcass mass (5.51 +/- 0.085 vs. 5.08 +/- 0.092 g; P < 0.001) and myofibrillar protein mass (1.62 +/- 0.045 vs. 1.49 +/- 0.048 g; P < 0.05), although the fractional content of fat in the carcass was lower (167 +/- 7.0 vs. 197 +/- 7.7 g/kg wet weight) in transgenic animals. There was no evidence of muscle hypertrophy and no change in the proportion of slow type I myofibres in the limb muscles of Rskalpha-actin/hIGF-I transgenic mice at 3 or 6 months of age. Phenotypic changes in Rskalpha-actin/hIGF-I mice are likely to be due to systemic as well as autocrine/paracrine effects of overproduction of IGF-I due to expression of the human IGF-I transgene. The effect of muscle specific over-expression of Rskalpha-actin/hIGF-I transgene was tested on: (i) muscle regeneration in auto-transplanted whole muscle grafts; (ii) myofibre atrophy following sciatic nerve transection; and (iii) sarolemmal damage and myofibre necrosis in dystrophic mdx muscle. No beneficial effect of muscle specific over-expression of Rskalpha-actin/hIGF-I transgene was seen in these three experimental models.

Fading of nipple-areolar reconstructions: the last hurdle in breast reconstruction?

Fading of nipple-areolar reconstructions is commonly reported, but there are few formal studies of this phenomenon. The purpose of this study was to determine whether deficiencies in nipple-areolar reconstruction and pigmentation were perceived by patients, their partners and independent observers, and whether a technique could be developed to measure nipple-areolar colour reliably. A total of 57 patients, 32 partners and four independent observers completed questionnaires about the appearance of the patients' breast reconstructions in general and specifically about their nipple-areolar reconstructions. Scores for the general attributes of the breast reconstruction were used as internal controls for the scores of the nipple-areolar reconstruction. A computer software package was developed to analyse colour in photographs of the reconstructions. Independent observers thought that nipple-areolar reconstruction improved the appearance of a breast reconstruction 81% of the time. Considerably fewer patients were happy with their nipple-areolar colour than were happy with the more general attributes of the breast reconstruction (P < 0.005). Colour analysis objectively demonstrated measurable mismatch between normal and reconstructed nipple-areolar skin, which was positively correlated with time since surgery due to fading of the nipple-areolar reconstruction. In our patients, the quality of nipple-areolar reconstruction, in particular its pigmentation, is seen as inferior to that of the rest of the breast reconstruction in the eyes of patients, their partners and independent observers. The poor colour match and fading of reconstructed nipple-areolar skin are phenomena that can be measured using colour analysis.

Short-term infusion of LongR(3) insulin-like growth factor (IGF)-I decreases hepatic IGF-I mRNA but not IGF binding protein-3 mRNA expression in pigs

Infusion of pigs with an insulin-like growth factor-I (IGF-I) analogue (LongR(3)IGF-I) that does not bind to IGF-binding proteins decreases growth rate and the plasma concentration of growth hormone (GH), IGF-I, IGFBP-3, and insulin. This study was designed to determine whether the decrease is due to changes in IGF-I and IGFBP-3 gene expression. IGF-I or LongR(3)IGF-I (180 microg/kg/day) was infused into 55-kg finisher pigs for 4 days using Travenol infuser pumps. Plasma IGF-I concentration was measured by radioimmunoassay and plasma IGFBP-3 and IGFBP-2 were estimated by Western ligand blotting. Steady-state levels of IGF-I and IGFBP-3 mRNA were measured by RNase protection assay. Neither IGF-I nor LongR(3)IGF-I had a significant effect on hepatic IGF-I class 1 mRNA expression, whereas hepatic IGF-I class 2 mRNA expression was significantly reduced by both peptides. Plasma IGFBP-3 levels were unaffected by IGF-I treatment but were reduced by LongR(3)IGF-I treatment. The decrease in IGFBP-3 was not due to decreased gene expression in porcine liver or kidney, since neither IGF-I nor LongR(3)IGF-I treatment altered IGFBP-3 mRNA. This study infers a direct effect of the IGF analogue LongR(3)IGF-I on GH through its inhibition of plasma IGF-I concentration and class 2 IGF-I mRNA. The decrease in plasma IGFBP-3 was not accompanied by a decrease in hepatic or renal IGFBP-3 mRNA, suggesting that in this case, plasma IGFBP-3 protein levels are posttranslationally regulated or are derived from tissues other than liver or kidney.

Delayed cholangitis resulting from a retained T-tube fragment encased within a stone: a rare complication

Inserting a T-tube after choledochotomy for the removal of bile duct stones remains a time-honored practice. Biliary drainage after bile duct exploration has some advantages. It minimizes bile leakage, provides access for cholangiography, and removes occasional retained stones. The use of T-tubes also has been associated with significant complications. Biliary sepsis, bile duct trauma during removal, bile leakage leading to peritonitis, retention of a fragment, stricture formation after removal have been reported. We report an unusual case of cholangitis caused by a T-tube fragment within a large stone, occurring 11 years after bile duct exploration. A 39-year-old woman underwent common bile duct exploration with insertion of a T-tube. Cholangiography was normal, but as the T-tube was removed, its horizontal limb was missing. The patient failed to present for endoscopic removal a few weeks after surgery Five years later, she presented with recurrent biliary pains and a mild episode of cholangitis. This last episode was associated with severe pain and jaundice. After initial conservative treatment, endoscopic retrograde cholangiopancreatography was performed, and endoscopic removal of the fragment and stone material was successful. Despite the declining numbers of bile duct explorations in the laparoscopic era and the tendency to use transcystic drainage or primary closure of a choledochotomy, the T-tube will continue to be a useful tool in biliary surgery, subject to consideration of the indications and the available alternatives. The reported case highlights the importance of careful tube preparation to prevent partial separation at removal, and early removal of a missing fragment to avoid potential serious complications.

Purification and molecular characterization of recombinant rat betacellulin

A method for the large scale expression and purification of rat betacellulin (BTC) from Escherichia coli has been developed using a cleavable fusion protein strategy. Insoluble fusion protein collected as inclusion bodies was dissolved in urea under reducing conditions, re-folded, and purified by gel filtration chromatography and C(4) RP-HPLC. Authentic rat BTC was obtained after proteolytic cleavage of the fusion protein with Factor Xa. Factor Xa cleaved an additional site within the BTC protein, generating a truncated isoform separable from full-length BTC by heparin-affinity chromatography. Recombinant rat BTC stimulated the proliferation of mouse Balb/c 3T3 fibroblasts and competed for binding to the ErbB1 receptor in a dose-dependent manner analogous to that of BTC purified from natural sources.

A milk growth factor extract reduces chemotherapeutic drug toxicity in epithelial cells in vitro

Transforming growth factor-beta (TGF-beta) and insulin-like growth factor (IGF-I) can attenuate drug-induced cell death in epithelial cells. Since milk whey contains a mixture of these and other growth factors, we evaluated mitogenic bovine whey extract (MBWE) for protective activity against chemotherapy drug damage in cultured epithelial cells (mink lung, MvlLu). Etoposide and vinblastine reduced cell survival by up to 90%. This was attenuated by the addition of MBWE before and during drug exposure, but not following drug removal. MBWE was compared with individual growth factors known to be present in the mixture. IGF-I and platelet-derived growth factor were ineffective, whereas TGF-beta2 induced growth inhibition and cell survival, with a maximum response at 3 ng/ml. TGF-beta2 bioactivity was also demonstrated by showing that acidification of MBWE (A-MBWE), to activate TGF-beta2, enhanced its growth inhibitory and chemoprotective activities 60- and 12-fold, respectively. However, MBWE contained additional protective factors. When TGF-beta2 and the MBWE preparations were compared, on the basis of growth inhibition equivalents, MBWE protected cells against drug toxicity at concentrations an order of magnitude lower than with TGF-beta2 or A-MBWE. Immunoneutralization of the TGF-beta present in MBWE and A-MBWE eliminated all growth inhibitory activity but not all cell survival activity. We conclude that the MBWE preparations are cytoprotective against two chemotherapy drugs when added before and during drug exposure. TGF-beta contributes to this activity, but the extracts contain other factors that promote the survival of epithelial cells after chemotherapy drug exposure.

Measurement of betacellulin levels in bovine serum, colostrum and milk

Betacellulin, a member of the epidermal growth factor (EGF) family, was originally isolated and identified from the conditioned medium from a murine pancreatic beta-cell carcinoma cell line. Recently, we isolated bovine betacellulin from a growth factor enriched cheese whey extract, but there is no information on the presence of betacellulin in other biological fluids. We have cloned the cDNA for bovine betacellulin, produced recombinant betacellulin and shown that it has a similar potency to the purified native molecule in stimulating the proliferation of Balb/c3T3 fibroblasts. We have produced a polyclonal antiserum to bovine betacellulin which did not cross-react with EGF or transforming growth factor-alpha (TGF-alpha). The antibody was used in a homologous RIA that was able to detect betacellulin in pooled bovine colostrum sampled during the first 3 days after calving (2.30+/-0.11 ng/ml mean+/-s.e.m.; n=6), in bovine milk soluble fraction (1.93+/-0.64 ng/ml mean+/-s.e.m.; n=5) and in bovine cheese whey (2.59+/-0.16 ng/ml mean+/-s.e.m.; n=3). The betacellulin concentration in foetal bovine serum (FBS) (3.68+/-0.59 ng/ml mean+/-s.e.m.; n=6) greatly exceeded that of betacellulin in serum from male calves 1 and 5 weeks of age (0.53+/-0.15 ng/ml and 0.70+/- 0.09 ng/ml respectively; mean+/-s.e.m.; n=9). Betacellulin measured in the serum of these same animals when aged between 27 and 43 weeks was below the detection limits of the RIA. Sera from 10 out of 36 unmated heifers contained betacellulin levels within the detection limits of the assay (0.433+/-0.06 ng/ml mean+/-s.e.m.; n=10). The presence of betacellulin in bovine colostrum and milk suggests that it plays a role in the growth and development of the neonate and/or mammary gland function. The results also show that betacellulin is undetectable in the castrated adult male circulation. Additionally, although present in very low amounts, serum betacellulin could be under hormonal regulation in the female, since betacellulin was detected in sera from 27% of the unmated heifers examined in this study. The high levels of betacellulin detected in FBS relative to newborn and adult serum suggests a possible endocrine role for this growth factor in the bovine foetus.

Structure-function and biological role of betacellulin

Betacellulin (BTC) belongs to the epidermal growth factor (EGF) family of peptide ligands that are characterised by a six-cysteine consensus motif that forms three intra-molecular disulfide bonds crucial for binding the ErbB receptor family. BTC was initially described, purified and cloned from a mouse insulinoma cell line. BTC is proteolytically processed from a larger membrane-anchored precursor and is a potent mitogen for a wide variety of cell types. BTC binds and activates ErbB-1 and ErbB-4 homodimers and is further characterised by its unique ability to activate all possible heterodimeric ErbB receptors. BTC is widely expressed in most tissues and various body fluids, including milk. Expression is particularly high in the pancreas where it is thought to play a role in the differentiation of pancreatic beta cells. While much is known about the ErbB receptor binding characteristics of BTC and its effect on a variety of cultured cells under different conditions, the challenge that lies ahead is to determine the role of BTC in vivo. This review will focus on the structure of BTC and the various biological effects ascribed to this member of the EGF family.

Mitogenic whey extract stimulates wound repair activity in vitro and promotes healing of rat incisional wounds

The ability of single growth factors to promote healing of normal and compromised wounds has been well described, but wound healing is a process requiring the coordinated action of multiple growth factors. Only the synergistic effect on wound healing of combinations containing at most two individual growth factors has been reported. We sought to assess the ability of a novel milk-derived growth factor-enriched preparation ¿mitogenic bovine whey extract (MBWE), which contains six known growth factors, to promote repair processes in organotypic in vitro models and incisional wounds in vivo. MBWE stimulated the contraction of fibroblast-populated collagen lattices in a dose-dependent fashion and promoted the closure of excisional wounds in embryonic day 17 fetal rat skin. Application of MBWE increased incisional wound strength in normal animals on days 3, 5, 7, and 10 and reversed the decrease in wound strength observed following steroid treatment. Wound histology showed increased fibroblast numbers in wounds from normal and steroid-compromised animals. These data suggest the mixture of factors present in bovine milk exerts a direct action on the cells of cutaneous wound repair to enhance both normal and compromised healing.

Identification of an alternatively spliced mRNA transcript of human betacellulin lacking the C-loop of the EGF motif and the transmembrane domain

This paper describes the cloning and characterization of a novel cDNA encoding a short form of betacellulin (BTC-beta), and reports the expression of this mRNA in a variety of human tissues and cell types. BTC-beta is likely the result of alternative splicing. This splicing event leads to the generation of an mRNA encoding an unusual BTC precursor in which the C-loop of the EGF domain and the transmembrane domain are deleted while the remainder of the mature molecule is fused in-frame to the C-terminal cytoplasmic tail.

Identification of betacellulin as a major peptide growth factor in milk: purification, characterization and molecular cloning of bovine betacellulin

Betacellulin (BTC), a member of the epidermal growth factor (EGF) family of peptide growth factors, was purified from a growth-factor-enriched whey fraction of bovine milk by a combination of ion-exchange chromatography, gel-filtration chromatography, affinity chromatography and reverse-phase HPLC. Bovine BTC (bBTC) had an apparent molecular mass of 21-22 kDa on SDS/PAGE and exists in a glycosylated form. The cDNA encoding bBTC was obtained by a combination of 5' and 3' rapid amplification of cDNA ends ('RACE'). The primary translation product consists of 178 amino acid residues containing a putative signal sequence, a transmembrane domain, the mature BTC domain and a cytoplasmic domain containing a highly hydrophilic Arg-Lys-rich region similar to that of mouse BTC and human BTC. The amino acid sequence of the bBTC precursor was 88% identical with human BTC and 79% identical with mouse BTC. The bBTC gene was found to be expressed in a wide range of tissues, including the mammary gland. The identification of BTC in milk raises the possibility that it has a major role in the growth and development of the neonatal gastrointestinal tract.

Effect of growth hormone administration on IGF binding protein-3 mRNA levels in porcine tissues

The effect of short-term GH treatment on steady-state insulin-like growth factor binding protein-3 (IGFBP-3) mRNA levels in liver, kidney, longissimus dorsi muscle, stomach and jejunum was examined in pigs. Ten female crossbred pigs were allocated to either saline or GH (70 microg/kg/day) treatment by subcutaneous injection for 4 days. They were allowed to feed ad libitum, and were weighed daily. At the end of the treatment period, the pigs were slaughtered and samples of liver, kidney, skeletal muscle, stomach and jejunum were collected and total RNA was extracted. Steady-state levels of IGFBP-3 mRNA were quantified by RNase protection assay and were compared with the level of IGF-I class 1 and class 2 transcripts. IGFBP-3 mRNA increased in response to GH in both liver and kidney, but not in the other tissues sampled. Hepatic IGF-I mRNA responded to short-term GH treatment with a fourfold increase in IGF-I class 1 mRNA and an eightfold increase in IGF-I class 2 mRNA, which was liver specific. IGF-I class 1 mRNA was not responsive to GH treatment in other tissues. The short-term nature of this treatment suggests that the increase in hepatic IGFBP-3 and IGF-I transcripts is a relatively early response to treatment with GH, and that the increase in plasma concentrations of IGFBP-3 in response to GH are derived from the liver, the kidney, or both.

The use of delay tanks in the management of radioactive waste from thyroid therapy

An underground system of tanks was installed to delay the discharge of 131I waste from the thyroid therapy unit to the on-site sewage treatment plant. As a consequence, the level of radioactivity discharged to sewage has fallen by a factor of 530, reducing the radiation dose to hospital and auxiliary service staff. Cancer patients are no longer required to collect their urine, hence increasing the hygiene for all concerned. A model was developed of iodine waste which estimates the dose rate above the delay tanks and the activity of iodine discharged. The maximum effective dose to a member of the public due to the holding tanks is 40 microSv.year-1. There is now better management of the radioactive waste from the iodine therapy ward.

Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs

Growth hormone (GH) improves growth performance in the pig. Analogues of insulin-like growth factor-I (IGF-I) that bind poorly to IGF binding proteins (IGFBP) stimulate growth in the rat but, in contrast, inhibit growth in the pig. This study was designed to determine the effect of IGF peptides alone or in combination with porcine GH (pGH) on growth characteristics and plasma hormone concentrations in finisher pigs. A four-day infusion of Long [R3] IGF-I (LR3IGF-I; 180 micrograms/kg/day) decreased the average daily gain, food intake, and plasma IGFBP-3, IGF-I and insulin concentrations. The mean plasma GH concentration was decreased by 23% and the area under the GH peaks was reduced by 60%. Co-administration of pGH (30 micrograms/kg/day) with LR3IGF-I had no interactive effect on growth performance, and plasma insulin, IGFBP-3 and IGF-I concentrations remained suppressed. The area under the GH peaks was not restored with this combination treatment although mean plasma GH concentrations were elevated in all animals receiving pGH. Infusion of IGF-I (180 micrograms/kg/day) decreased plasma insulin and mean GH concentrations but had no significant effect on IGFBP-3 concentrations. Average daily gain and feed intake were not changed by IGF-I treatment. A combination of IGF-I and pGH injection (30 micrograms/kg/day) increased plasma IGFBP-3 concentrations but plasma insulin levels remained suppressed. Plasma glucose levels were unaffected by any treatment. The study demonstrates that both IGF-I and LR3IGF-I suppress plasma GH concentrations in finisher pigs. This, in turn, may be responsible for the reduction in the plasma concentration of IGF-I, IGFBP-3 and insulin seen in LR3IGF-I-treated animals. The decrease in these parameters may contribute to the inhibitory effect of LR3IGF-I on growth performance in the pig.

Normalization of ion transport in murine cystic fibrosis nasal epithelium using gene transfer

The murine nasal epithelium was investigated by the short-circuit current (SCC) technique. Electrogenic sodium absorption was revealed by addition of amiloride and calcium-dependent chloride secretion by the addition of amiloride and calcium-dependent chloride secretion by the addition of 2,5-di-(tert-butyl)-1,4-benzohydroquinone (TBHQ)/ionomycin. In the presence of these agents a further increase in SCC was obtained by addition of forskolin. Epithelia from both cystic fibrosis (CF) null (Cftrtm1Cam) and CF delta F508 (Cftrtm2Cam) mice had enhanced sodium absorption compared with controls, whereas only delta F508 epithelia had increased calcium-dependent chloride secretion. Both strains gave nasal epithelia that showed significantly reduced responses to forskolin, due to the absence of CF transmembrane conductance regulator (CFTR) chloride channels. In Cftrtm2Cam nasal epithelia the forskolin responses were not significantly different from zero. Transfection of these mice with the plasmid pTRIAL10-CFTR2 complexed with cationic liposomes normalized the transporting activity in the nasal epithelium. Basal SCC and calcium-dependent chloride secretion were significantly reduced, whereas CFTR-dependent chloride secretion was increased to normal values. Amiloride-sensitive SCC was reduced by transfection but failed to reach significance. The similarity of murine CF nasal epithelium to that in human CF airways makes the model valuable for gene therapy studies.

Platelet-derived growth factor, insulin-like growth factors, fibroblast growth factors and transforming growth factor beta do not account for the cell growth activity present in bovine milk

Cation-exchange chromatography effectively concentrates the cell growth activity present in whey and we have used this process as a basis to characterise further the growth factors present in bovine milk. Under neutral conditions, total bioactivity in the growth factor-enriched cation-exchange fraction chromatographed with an apparent molecular mass of 80-100 kDa. In contrast, acid gel-filtration chromatography resolved two peaks of cell growth activity. A peak at 15-25 kDa contained the bulk of growth activity for Balb/c 3T3 fibroblasts while bio-activity for L6 myoblasts and skin fibroblasts eluted with a molecular mass of 6 kDa. A peak of inhibitory activity for Mv1Lu and MDCK cells also eluted at 15-25 kDa. Both IGF-I and IGF-II were purified from fractions that eluted at 6 kDa, although the IGF peptides alone did not account for the total bioactivity recovered. Platelet-derived growth factor (PDGF), identified by radioreceptor assay, eluted at a slightly higher molecular mass than the peak of growth activity for Balb/c 3T3 cells, and an anti-PDGF antibody was without effect on the growth of Balb/c 3T3 cells in response to the whey-derived factors. Further purification of the inhibitory activity for epithelial cells yielded a sequence for transforming growth factor beta (TGF-beta), and all inhibitory activity for Mv1Lu cells was immunoneutralised by an antibody against TGF-beta. In contrast, this antibody decreased the growth of Balb/c 3T3 fibroblasts in the whey-derived extract by only 10%. Finally, a cocktail of recombinant growth factors containing IGF-I, IGF-II, PDGF, TGF-beta and fibroblast growth factor 2 stimulated growth of Balb/c 3T3 cells to a level equivalent to only 51% of that observed in the milk-derived growth factor preparation. We conclude that: (i) cell growth activity recovered from bovine whey is present in acid-labile high molecular weight complexes; (ii) all cell growth inhibitory activity for epithelial cells can be accounted for by TGF-beta; (iii) IGF-I and IGF-II co-elute with the major peak of activity for L6 myoblasts and skin fibroblasts, although the IGF peptides alone do not explain the growth of these cells in the whey-derived extract; and (iv) neither PDGF nor TGF-beta account for the 15-25 kDa peak of Balb/c 3T3 growth activity. These data suggest the presence of additional mitogenic factors in bovine milk.

Transforming growth factor beta in bovine milk: concentration, stability and molecular mass forms

Transforming growth factor beta (TGF-beta) is one of the predominant growth factors present in milk. The concentration, molecular mass forms and stability of TGF-beta in bovine milk were investigated using a standard bioassay measuring the growth inhibition of a milk lung epithelial cell line. Most of the TGF-beta bioactivity in milk was found to be in a latent form, which was also retained in the whey fraction. After acid activation, the total TGF-beta concentration was 4.3 +/- 0.8 ng and 3.7 +/- 0.7 ng TGF-beta per ml of milk and cheese whey respectively. Cation-exchange chromatography at pH 6.5 was used to concentrate latent whey-derived TGF-beta, which could be activated by transient exposure to extremes of pH, urea or heat. Heparin did not significantly activate milk-derived TGF-beta. Neutral gel filtration of the cationic whey fraction revealed a major peak of latent TGF-beta with a molecular mass of 80 kDa and a smaller peak at 600 kDa. Transient acidification of the cationic whey fraction prior to neutral gel filtration, or gel filtration under acidic conditions, released low molecular mass TGF-beta from both high molecular mass peaks. Whey-derived TGF-beta was purified using a five-step chromatographic procedure. An N-terminal sequence was obtained for TGF-beta 2, which accounted for over 85% of the TGF-beta bioactivity in whey. All TGF-beta activity in whey could be neutralised by a monoclonal antibody directed against TGF-beta 1, -beta 2 and -beta 3. The results suggest that the majority of TGF-beta in bovine milk is present in a small latent complex.

Divergent selection for high or low growth rate modifies the response of muscle cells to serum or insulin-like growth factor-I in vitro

Genetic differences in growth potential could result from changes in the levels of growth stimulatory factors or in the response of target tissues. The latter possibility was tested in adult myoblasts prepared from chickens selected for high (HG) or low growth rate (LG). Stimulation of [3H]-thymidine incorporation into DNA by serum was of higher amplitude in HG than LG muscle cells irrespective of whether the cell preparations were enriched in myoblasts or fibroblasts. HG myoblasts were also more responsive to insulin-like growth factor-I (IGF-I) in terms of [3H]-thymidine incorporation. IGF analogues with a reduced affinity for IGF binding proteins gave similar results suggesting that activity of binding proteins could not explain the difference between cells from the HG and LG lines. This difference was restricted to the proliferative stage because in myotubes, basal or IGF-I stimulated glucose and amino acid transports, tyrosine incorporation and protein degradation were not different.

New opportunities from the isolation and utilization of whey proteins

Management of dairy whey has often involved implementation of the most economical disposal methods, including discharge into waterways and onto fields or simple processing into low value commodity powders. These methods have been, and continue to be, restricted by environmental regulations and the cyclical variations in price associated with commodity products. In any modern regimen for whey management, the focus must therefore be on maximizing the value of available whey solids through greater and more varied utilization of the whey components. The whey protein constituents offer tremendous opportunities. Although whey represents a rich source of proteins with diverse food properties for nutritional, biological, and functional applications, commercial exploitation of these proteins has not been widespread because of a restricted applications base, a lack of viable industrial technologies for protein fractionation, and inconsistency in product quality. These shortcomings are being addressed through the development of novel and commercially relevant whey processing technologies, the preparation of new whey protein fractions, and the exploitation of the properties of these fractions in food and in nontraditional applications. Examples include the following developments: 1) whey proteins as physiologically functional food ingredients, 2) alpha-lactalbumin and beta-lactoglobulin as nutritional and specialized physically functional food ingredients, and 3) minor protein components as specialized food ingredients and an important biotechnological reagents. Specific examples include the isolation and utilization of lactoferrin and the replacement of fetal bovine serum in tissue cell culture applications with a growth factor extract isolated from whey.

Decreased muscle cell proliferation in chicks with a deletion in the GH receptor gene

The increase in muscle weight in neonatal animals is a consequence of increased protein accretion and DNA content. GH increases protein accretion but direct effects of GH on myogenic cell proliferation have not been demonstrated. Sex-linked dwarfism in the chick is caused by mutation or deletion in the GH receptor gene and has provided a useful model to study the physiological consequences of GH insensitivity. This study determined the consequences of GH receptor gene mutation on muscle cell proliferation in vivo. Northern and Southern blotting and PCR analysis revealed restriction fragment length polymorphism patterns and a 1.7 kb deletion of the intracellular domain of the GH receptor gene in commercial dwarf broiler chicks, similar to the Connecticut strain in which there is a dysfunctional GH receptor. Cell proliferation was measured in muscle sections from normal and dwarf chicks after incorporation of 5-bromo-2'-deoxyuridine (BrdU; 25 mg/kg) in vivo at 2, 5 and 13 days of age. Incorporation of BrdU into nuclei was measured in frozen sections, counterstained with propidium iodide to estimate the total number of nuclei by quantitative image analysis, and the labelling index was calculated. Paraffin-embedded sections of breast muscle were stained using an anti-human IGF-I polyclonal antibody. Expression of IGF-I mRNA in muscle from each genotype at 5 days of age was measured by RNAse protection assay. The labelling index was similar in 2-day-old chicks from both genotypes (normal, 20.14 +/- 2.39%; dwarf, 19.79 +/- 5.83%). By day 5 the labelling index had decreased but was significantly higher (P < 0.02) in normal (12.53 +/- 3.36%) compared with the dwarf (6.25 +/- 1.39%). By 13 days of age, there was a further decrease in labelling index but no difference between the groups (normal, 4.92 +/- 1.28%; dwarf, 4.96 +/- 1.51%). IGF-I mRNA was expressed and IGF-I peptide was identified in muscle sections but there was no difference between genotypes. The results show that cell division in breast muscle in vivo is high in neonatal chicks but it declines with increasing age. The absence of a functional GH receptor in the dwarf is associated with a greater decline in DNA synthesis and suggests that GH may directly affect a proportion of cells, since there was no difference in IGF-I mRNA or peptide.

Production of a human epidermal growth factor fusion protein and its degradation in rat gastrointestinal flushings

This study describes the biosynthesis of a human epidermal growth factor fusion protein, Long EGF, that has a 53 amino acid extension peptide derived from the 46 N-terminal amino acids of porcine GH. The approach allowed the production of Long EGF at high efficiency due to the expression of the fusion protein in high yield as inclusion bodies in Escherichia coli. Long EGF had a slightly lower potency compared with native EGF in a range of assays, including binding to anti-EGF antibodies or the EGF receptor, stimulation of Balb/3T3 fibroblast and rat intestinal epithelial cell growth, as well as counteracting the inhibition of mink lung epithelial cell proliferation by transforming growth factor-beta 1. Degradation of Long EGF and native EGF was compared in gastrointestinal flushings as an indication of whether the EGF domain of the fusion protein would be protected from proteolytic cleavage and be useful as a trophic agent in the gut. Incubation with flushings from the stomach or jejunum of rats caused rapid cleavage of the extension peptide, releasing native EGF. A C-terminal truncation of Arg53 in the stomach and a removal of the C-terminal pentapeptide (49 Trp-Trp-Glu-Leu-Arg53) in the small bowel was demonstrated by N-terminal sequencing and mass spectrometry. The degradation patterns were reflected by changes in migration of products on SDS-PAGE and in subsequent binding activities to the EGF receptor and anti-EGF antibodies. The data show that a human EGF fusion protein can be produced efficiently in a bacterial expression system and that it retains biological activity in vitro. Although the extension peptide was rapidly cleaved from Long EGF in both stomach and small bowel producing similar biological activity to native EGF, it could not prevent subsequent degradation of the EGF domain. Other strategies are being investigated to develop an effective oral form of EGF that resists digestion by proteases in the gastrointestinal tract.

Porcine osteochondrosis: deficiencies in transforming growth factor-beta and insulin-like growth factor-I

Osteochondrosis and dyschondroplasia are common multifocal disturbances of endochondral ossification in many species of domestic animals, and are characterized by the retention of avascular cartilage. These cartilage disorders are characterized by a failure of chondrocyte differentiation, matrix mineralisation and its replacement by bone. Rabbit polyclonal antibodies to transforming growth factor-beta (TGF-beta) and to insulin-like growth factor-I (IGF-I) were used to detect the two growth factors in normal and osteochondrotic porcine epiphyses. In the normal pig epiphyses IGF-I and TGF-beta were present in the chondrocytes of the epiphyseal hyaline cartilage and IGF-I was readily localised to the hypertrophic chondrocytes in the growth cartilage adjacent to the epiphyseal ossification centre. Both growth factors were found to be deficient in chondrocytes at sites of osteochondrosis. Both these growth factors are thought to be involved in the cascade of events associated with chondrocyte function during endochondral ossification. Deficiencies in TGF-beta and IGF-I demonstrated in porcine osteochondrosis and previously shown in avian dyschondroplasia suggest further similarities in the pathogenesis of these conditions.

Regulation of chick muscle satellite cells by fibroblast growth factors: interaction with insulin-like growth factor-I and heparin

This study describes the effect of acidic and basic fibroblast growth factor (FGF) on DNA synthesis in chick satellite cells in vitro and interactions with insulin-like growth factor-I (IGF-I) and exogenous heparin. Basic bFGF stimulated incorporation of [3H]thymidine into DNA with a half-maximum concentration (ED50) of 3.23 +/- 0.33 pmol/l, more than 500-fold more potent than acidic FGF (ED50 = 2.13 +/- 0.5 nmol/l). Both bFGF and IGF-I allowed the cells to traverse the cell cycle with an approximate length of the G1 phase of 12 h. When cells were incubated with bFGF and IGF-I together their effects on DNA synthesis were additive rather than synergistic throughout the full concentration range. Incubation of satellite cells with low concentrations of heparin (ng/ml) to mimic the effect of endogenous heparan sulphate proteoglycan caused a small increase in DNA synthesis, whereas higher concentrations (microgram/ml) inhibited DNA synthesis in a dose-related manner. A low concentration of heparin increased DNA synthesis at the highest concentration of bFGF, but high doses of heparin inhibited the response to bFGF throughout the dose-response curve but without altering the ED50. RNAse protection assay showed the expression of bFGF mRNA in proliferating cells which appeared to decrease on differentiation. The results suggest that aspects of neonatal muscle development are regulated by interactions between autocrine/paracrine growth factors such as IGF-I and bFGF, perhaps IGF-I derived from the circulation, and components of the extracellular matrix. Concentrations of the matrix components may change throughout the neonatal period and into adulthood and have an important effect on the regulatory role played by the growth factors.

Increased expression and activity of ornithine decarboxylase in chicks genetically selected for rapid growth rate

Polyamines are essential requirements for cell proliferation and their role in stimulation of RNA, DNA, and protein synthesis is clearly established. Ornithine decarboxylase is a key enzyme in the biosynthesis of the polyamines and its activity is regulated in response to factors that stimulate cell proliferation. Steady-state ODC mRNA levels and enzyme activity were measured in muscle of chicks genetically selected for increased growth rate or for egg production. In muscle, muscle satellite cells and myotubes, two ODC mRNA transcripts are present of molecular size 2.05 and 1.75 kb. Northern blotting analysis suggest that these transcripts are produced as a result of using different polyadenylation sites. Between day 1 and day 6 after hatching, a period of rapid muscle growth in these animals, a peak in muscle ODC mRNA levels is followed by a peak in enzyme activity in both lines. Significantly higher ODC mRNA levels and enzyme activity are associated with selection for rapid growth in the broiler line. The results are consistent with other data showing that ODC is a major factor in cell growth and provide further evidence that it is a candidate 'trait-gene' for growth.

Identification of tricyclic analogs related to ellagic acid as potent/selective tyrosine protein kinase inhibitors

The plant-derived natural product ellagic acid (1) has recently been identified as a potent, though nonselective, inhibitor of the tyrosine-specific protein kinase pp60src. This report details efforts directed toward the identification of tricyclic structures related to ellagic acid, with enhanced specificity for inhibition of pp60src over other protein kinases. Phenanthridinone and carbazole core structures were selected for investigation, since N-functionalization allows for the synthesis of numerous analogs which can be utilized to probe enzyme-inhibitor interactions. These ring systems were prepared via a general sequence of biaryl bond formation followed by cyclization to form the desired tricyclic ring systems. N-Alkylation, -acylation, or -sulfonylation and deprotection with boron tribromide afford the target tetraphenolic phenanthridinones 5 and carbazoles 9. Several analogs from both of these series have potencies comparable to that of 1 and exhibit substantially enhanced selectivities for inhibition of pp60src relative to protein kinase A (PKA), a serine/threonine protein kinase. Carbazole-based analogs 9j,m,p are submicromolar inhibitors of pp60src, with potency for the target tyrosine kinase comparable to that of ellagic acid (1), however with 2 orders of magnitude greater selectivity versus that for PKA. As seen for ellagic acid, members of the phenanthridinone-based series (e.g., 5a) exhibited inhibition of pp60src in a manner which is partial mixed noncompetitive with respect to ATP, while analogs in the carbazole series (e.g., 9a) inhibit pp60src in an ATP competitive manner.

Plasma concentrations of growth hormone and insulin-like growth factor-I in chickens developing tibial dyschondroplasia

The concentrations of plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I) were measured in broilers during the initial development of tibial dyschondroplasia. Chicks were fed a standard starter ration, or a diet imbalanced in calcium and phosphorus to increase the incidence of dyschondroplasia. At 14 days of age four blood samples were collected and assayed for GH and IGF-I. The chicks were killed at three weeks of age and sections of bone were assessed histologically for evidence of dyschondroplasia. All the chicks displayed a pulsatile pattern of GH secretion. Eight of the group fed the imbalanced diet developed dyschondroplasia which was accompanied by a significant increase in the mean and peak GH concentrations compared with the control group but no increase in basal concentrations. The chicks fed the imbalanced diet which did not develop dyschondroplasia were not different from the control birds. There were no differences in IGF-I concentrations between the groups.

Plasma growth hormone and insulin-like growth factor-I (IGF-I) concentrations at the onset of lay in ad libitum and restricted broiler breeder fowl

1. Plasma concentrations of growth hormone (GH) and insulin-like growth factor I(IGF-I) were determined in individually caged broiler breeder females from 17 to 30 weeks of age. The birds were fed ad libitum or restricted during rearing in a randomised block design. Restricted birds were fed ad libitum after laying an egg and egg production was recorded to 54 weeks. 2. GH concentrations were higher in restricted compared with ad libitum-fed birds at 17 to 21 weeks of age and were similar thereafter. Plasma IGF-I concentrations were higher in restricted compared with ad libitum-fed birds throughout the sampling period of the experiment. 3. The age at first egg was delayed by about two weeks in restricted birds. At 54 weeks of age they had laid 114 compared with 67 eggs in birds fed ad libitum throughout and had produced less than half the number of eggs with defective shells. 4. It was suggested that differences in egg production between ad libitum and restricted broiler breeder females could be related to changes in the pattern of GH and/or IGF-I secretion.

Insulin-like growth factor-I in the ovary of the laying hen: gene expression and biological actions on granulosa and thecal cells

Concentrations of insulin-like growth factor-I (IGF-I) were measured in granulosa and thecal tissue dissected from the three largest follicles in the ovaries of laying hens. The higher concentration was found in extracts of granulosa (0.82 +/- 0.01 pmol/g wet wt) and theca (0.36 +/- 0.02), both of which were greater than that in liver extracts (0.25 +/- 0.01). RNA was extracted from these tissues, and by using reverse transcription and the polymerase chain reaction with primers specific for chicken IGF-I, both granulosa and thecal tissue were shown to express chicken IGF-I mRNA. Granulosa and thecal cell cultures were established and used to measure IGF binding sites and the response to exogenous IGF peptides in terms of DNA synthesis. Both cell types bound [125I]IGF-I, which was displaced by IGF-I, IGF-II, and insulin in descending order of potency, characteristic of a type-I IGF receptor. Treatment of granulosa and thecal cell cultures with IGF-I resulted in a dose-dependent increase in [3H]thymidine incorporation into DNA by both cell types. LH, but not FSH, stimulated DNA synthesis in cultured granulosa cells but not in cultured thecal cells. This effect was enhanced in granulosa cells by the addition of IGF-I to the culture medium. These data are consistent with an autocrine or paracrine role for IGF-I within the developing ovarian follicle of the domestic hen.

Rapidly growing broiler (meat-type) chickens: their origin and use for comparative studies of the regulation of growth

1. Rapidly growing (meat-type) chickens have been intensively selected for over 50 years and grow up to four times faster than "layer" strains selected for reproductive traits. 2. Comparison between these lines are increasingly being used to study mechanisms underlying lean tissue growth. 3. Selection for increased growth has resulted in some undesirable consequences such as poor reproductive performance, excessive fatness, increased skeletal abnormalities and ascites. 4. The biochemistry, physiology and molecular biology of these changes are reviewed.

Regulation of amino acid transport and protein metabolism in myotubes derived from chicken muscle satellite cells by insulin-like growth factor-I

The effects of insulin and insulin-like growth factor-I (IGF-I) on amino acid transport and protein metabolism were compared in myotubes derived from chicken breast muscle satellite cells. Protein synthesis was assessed by continuous labelling with [3H]-tyrosine. Protein degradation was estimated by the release of trichloroacetic acid (TCA) soluble radioactivity by cells which had been previously labelled with [3H]-tyrosine for 3 days. Amino acid transport was measured in myotubes incubated in Dulbecco's modified Eagle's medium (DMEM) 0.5% bovine serum albumin (BSA) with or without insulin or IGF-I. Subsequent [3H]-aminoisobutyric acid (AIB) uptake was then measured in amino acid-free medium. IGF-I was more efficient than insulin at equimolar concentration (3.2 nmol/l) in stimulating protein synthesis (127 and 113% of basal, respectively) and inhibiting protein degradation (32% and 13% inhibition of protein degradation following 4 h incubation). Half maximal effective concentrations for stimulation of AIB uptake were 0.27 +/- 0.03 nmol/l and 34.8 +/- 3.1 nmol/l for IGF-I and insulin respectively, with maximal stimulation of about 340% of basal. Cycloheximide (3.6 mumol/l) diminished IGF-I-stimulated AIB uptake by 55%. Chicken growth hormone had no effect on basal AIB uptake in these cells and neither glucagon nor dexamethasone had an effect on basal or IGF-I-stimulated AIB uptake. This study demonstrates an anabolic effect for IGF-I in myotubes derived from primary chicken satellite cells which is mediated by the type I IGF receptor, since the cation-independent mannose 6-phosphate receptor does not bind IGF-II in chicken cells.

Regulation of adipocyte precursor DNA synthesis by acidic and basic fibroblast growth factors: interaction with heparin and other growth factors

The development of adipose tissue is dependent on the growth and differentiation of fibroblast-like adipocyte precursor cells. Culture of adipocyte precursor cells in vitro has provided an ideal system for identifying potential regulators of proliferation and differentiation. We have demonstrated that both acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) stimulate chicken adipocyte precursor DNA synthesis in a dose-dependent manner up to a concentration of 100 micrograms aFGF/l and 1 microgram bFGF/l. The effect of bFGF was biphasic, so that in incubations with 25 micrograms bFGF/l, DNA synthesis was not significantly different from controls. In the presence of heparin, stimulation of DNA synthesis at 25 micrograms bFGF/l was 1.6-fold greater than at a concentration of 1 microgram bFGF/l. Addition of heparin to incubations containing aFGF reduced the concentration required for maximum stimulation of DNA synthesis to 1 microgram/l. Cells incubated with aFGF (1-100 micrograms/l) in combination with insulin-like growth factor-I (IGF-I), platelet-derived growth factor, transforming growth factor-alpha or transforming growth factor-beta 1 (TGF-beta 1) exhibited a marked synergistic increase in DNA synthesis. This was also the case when 1 microgram bFGF/l was used, but at a concentration of 25 micrograms bFGF/l synergy was only seen with IGF-I and TGF-beta 1. These results suggest that both basic and acidic FGF are potentially important regulators of adipocyte hyperplasia and that their effect is modulated by constituents of the extracellular matrix and the presence of other growth factors.

Insulin-like growth factor-I-stimulated glucose transport in myotubes derived from chicken muscle satellite cells

The effects of insulin and insulin-like growth factor-I (IGF-I) on glucose transport were compared in myotubes derived from chicken breast muscle satellite cells in vitro. Myotubes were incubated (for 0.5 or 4 h) with or without glucose in the presence or absence of insulin or IGF-I. Glucose uptake was subsequently measured by the incorporation of 2-[1,2-3H(N)] deoxy-D-glucose ([3H]2DG) in glucose-free medium (10 min at 20 degrees C). Glucose uptake was almost completely abolished by the addition of cytochalasin B or phloretin. It was increased by a decrease in glucose concentration in the incubation medium. Insulin (5 mg/l) stimulated [3H]2DG uptake to a maximum of 43 +/- 10% above basal after 30-min incubation and 101 +/- 15% after 4-h incubation. IGF-I and insulin at equimolar concentrations (25 micrograms/l and 20 micrograms/l respectively) were almost equipotent after 0.5 h but after 4-h incubation IGF-I was 17-fold more potent, suggesting that this 'late' effect was mediated through the IGF-I receptor. Incubation with cycloheximide suggested that the effect of IGF-I involved increased protein synthesis. The results suggest that chicken myotubes express a glucose transporter which is regulated by IGF-I and glucose concentration. However, they do not appear to express a typical insulin-responsive transport system.