Fibrinogen Early In Severe paediatric Trauma studY (FEISTY junior): protocol for a randomised controlled trial

INTRODUCTION

Trauma causes 40% of child deaths in high-income countries, with haemorrhage being a leading contributor to death in this population. There is a growing recognition that fibrinogen and platelets play a major role in trauma-induced coagulopathy (TIC) but the exact physiological mechanisms are poorly understood.

METHODS AND ANALYSIS

This is a prospective multicentre, open-label, randomised, two-arm parallel feasibility study conducted in the emergency departments, intensive care units and operating theatres of participating hospitals. Severely injured children, aged between 3 months and 18 years, presenting with traumatic haemorrhage requiring transfusion of blood products will be screened for inclusion.Sixty-eight patients will be recruited and will be allocated to fibrinogen replacement using fibrinogen concentrate (FC) or cryoprecipitate in a 1:1 ratio. Fibrinogen replacement will be administered to patients with a FIBTEM A5 of ≤10. All other aspects of the currently used rotational thromboelastometry-guided treatment algorithm and damage-control approach to trauma remain the same in both groups.The primary outcome is time to administration of fibrinogen replacement from time of identification of hypofibrinogenaemia. Clinical secondary outcomes and feasibility outcomes will also be analysed.

ETHICS AND DISSEMINATION

This study has received ethical clearance from the Children's Health Queensland Human Research Ethics Committee (HREC/17/QRCH/78). Equipment and consumables for sample testing have been provided to the study by Haemoview Diagnostics, Werfen Australia and Haemonetics Australia. FC has been provided by CSL Behring, Australia. The funding bodies and industry partners have had no input into the design of the study, and will not be involved in the preparation or submission of the manuscript for publication.The use of viscoelastic haemostatic assays and early fibrinogen replacement has the potential to improve outcomes in paediatric trauma through earlier recognition of TIC. This in turn may reduce transfusion volumes and downstream complications and reduce the reliance on donor blood products such as cryoprecipitate.The use of FC has implications for regional and remote centres who would not routinely have access to cryoprecipitate but could store FC easily. Access to early fibrinogen replacement in these centres could make a significant impact and assist in closing the gap in trauma care available to residents of these communities.Outcomes of this study will be submitted for publication in peer-reviewed journals and submitted for presentation at national and international scientific fora.

TRIAL REGISTRATION NUMBER

NCT03508141.

Determination of Percentage of RoundUp Ready® Soya in Soya Flour Using Real-Time Polymerase Chain Reaction: Interlaboratory Study

An interlaboratory study was conducted to evaluate a method for determination of the percentage of RoundUp Ready® (RR) soya in soya flour using Taqman® technology. The method included DNA extraction from the test portion with cetyltrimethylammonium bromide buffer followed by chloroform extraction and Wizard® resin cleanup steps. The DNA was then assayed with primer and probe sets specific for lectin as the endogenous control and the RR insert as the target. The percentage of RR soya in the soya fraction of the sample was calculated by using a matrix-matched standard curve. Ten samples of split-level blind duplicates were sent to 22 laboratories in 12 countries worldwide. Test portions contained 0, 0.5, 0.7, 1.6, 2, and 3.9% (w/w) RR soya prepared gravimetrically from commercially available RR standard reference materials. Based on the results for test materials, the relative standard deviation for repeatability (RSDr) for the method ranged from 9.3 to 19.3% and, for reproducibility (RSDR), ranged from 20.3 to 33.7%.

Case Report: Fatal Pediatric Melioidosis Despite Optimal Intensive Care

With prompt administration of appropriate antimicrobial therapy and access to modern intensive care support, fatal pediatric melioidosis is very unusual. We describe cases of two children in whom the possibility of melioidosis was recognized relatively early, but who died of the disease, despite receiving optimal supportive care. We discuss the resulting implications for bacterial virulence factors in disease pathogenesis.

Primary amoebic meningoencephalitis in North Queensland: the paediatric experience

Primary amoebic meningoencephalitis (PAM) is a fulminant, diffuse haemorrhagic meningoencephalitis caused by Naegleria fowleri, with an almost invariably fatal outcome. In Australia and the developed world, PAM remains a rare disease, although it is very likely that large numbers of cases go undetected in developing countries. N. fowleri is a thermophilic, free-living amoeba with a worldwide distribution. It is acquired when contaminated fresh water is flushed into the nose and penetrates the central nervous system via the cribriform plate. Clinical features are similar to those of bacterial meningitis, but it does not respond to standard therapy and rapid progression to death occurs in most cases. Some survivors have been reported; these patients received early treatment with amphotericin B in combination with a variety of other medications. Our review describes the local and worldwide experience of this disease and its clinical features, and discusses the associated diagnostic challenges. We hope that by detailing the local response to a recent case, and the outcomes of our public health campaign, we can improve the knowledge of this rare disease for doctors working in rural and remote Australia.

Maintaining stable symptom control in inflammatory bowel disease: a retrospective analysis of adherence, medication switches and the risk of relapse

BACKGROUND

Maintenance therapy with 5-aminosalicylic acid (5-ASA) is a key strategy for preventing relapse in many patients with inflammatory bowel disease (IBD). Factors which disrupt 5-ASA delivery, such as non-adherence and 5-ASA switches, may destabilise symptom control.

AIM

To investigate the impact of non-adherence and medication switches on stable symptom control in UK patients with IBD.

METHODS

A retrospective cohort study was conducted using a UK dispensing database. Adherence was analysed in randomised matched samples for each of the six leading oral mesalazine formulations, measured by medication possession ratio (MPR); MPR ≥80% was classified as adherent. Relationships among adherence, switch and relapse were analysed over 18 months in patients receiving continuous mesalazine therapy throughout a 6-month baseline period (primary subgroup analysis). Relapses of active ulcerative colitis were identified using a doubling of MPR as a proxy.

RESULTS

Only 39% of patients in the matched samples (n = 1200) were classed as adherent. No significant differences in adherence were observed among mesalazine formulations. In the primary subgroup analysis (n = 568), non-adherent patients had a significantly greater risk of relapse than adherent patients (RR = 1.44, 95% CI = 1.08-1.94; P = 0.014). Among adherent patients (n = 276), those who switched had a 3.5-fold greater risk of relapse than those who did not switch (95% CI = 1.16-10.62; P = 0.008).

CONCLUSIONS

Both non-adherence and mesalazine switches in adherent patients were associated with significant increases in the risk of relapse, suggesting that disruption of mesalazine maintenance therapy may destabilise symptom control. These findings provide evidence to advocate caution when considering mesalazine switches for stable patients.

Virolysis of feline calicivirus and human GII.4 norovirus following chlorine exposure under standardized light soil disinfection conditions

The relationship between the infectivity of the feline calicivirus (FCV) vaccine strain F-9 and capsid destruction (virolysis) in response to available chlorine was investigated under standardized light soil disinfection conditions. Virolysis was measured using RNase pretreatment (in order to destroy exposed RNA following chlorine treatment) and quantitative reverse transcription PCR. A comparison between the results of plaque assays and virolysis following exposure of FCV F-9 grown in tissue culture to different concentrations of available chlorine showed a similar log-linear relationship, with >4-log reductions occurring at 48 and 66 ppm, respectively. Three non-epidemiologically linked human GII.4 noroviruses (NoVs) present in dilute clinical samples showed behavior similar to each other and were 10 times more resistant to virolysis than cultured FCV F-9. FCV F-9 when present in dilute human GII.4 samples acquired increased resistance to virolysis approaching that of human NoVs. This study represents a direct comparison between the virolysis of a surrogate virus (FCV F-9) and that of human GII.4 NoVs within the same matrix in response to available chlorine. The results support the view that matrix effects have a significant effect on virus survival.

Yttrium 90–Labeled Ibritumomab Tiuxetan Radioimmunotherapy Produces High Response Rates and Durable Remissions in Patients with Previously Treated B-Cell Lymphoma

We report updated time-to-event variables of a phase III randomized study comparing yttrium 90-labeled ibritumomab with rituximab standard therapy in 143 rituximab-naive patients with relapsed or refractory low-grade, follicular, or transformed CD20+ non-Hodgkin's lymphoma (NHL). Most patients (79%) had follicular lymphoma. Patients were randomized to receive a single intravenous (I.V.) dose of 90Y ibritumomab tiuxetan 0.4 mCi/kg (n = 73) or rituximab 375 mg/m2 I.V. weekly for 4 doses (n = 70). The radioimmunotherapy group was pretreated with 2 rituximab doses (250 mg/m2) to improve biodistribution and one dose of Indium 111-labeled ibritumomab tiuxetan for imaging. The overall response rate was 80% versus 56% (P = 0.002) and complete response (CR)/CR unconfirmed (CRu) rates were 34% for 90Y ibritumomab tiuxetan versus 20% for rituximab. With a median follow-up of 44 months, the data are mature as all ongoing patients in both groups exceeded the median Kaplan-Meier estimated time to progression (TTP), duration of response (DR), and time to next therapy. Although this study was not powered to detect differences in time-to-event variables, the results from this randomized trial demonstrate trends toward longer median TTP (15 vs. 10.2 months; P = 0.07), DR (16.7 vs. 11.2 months; P = 0.44) and time to next therapy (21.1 vs. 13.8 months; P = 0.27) in follicular NHL patients treated with 90Y ibritumomab tiuxetan compared with the rituximab control arm. In patients achieving a CR/CRu, the median TTP was 24.7 months for patients treated with 90Y ibritumomab tiuxetan compared with 13.2 months for rituximab-treated patients (P = 0.41), and ongoing responses of > 5 years have been observed. These results confirm that 90Y ibritumomab tiuxetan produces high response rates and durable remissions in patients with previously treated low-grade, follicular, and transformed NHL.

Durable responses after ibritumomab tiuxetan radioimmunotherapy for CD20+ B-cell lymphoma: long-term follow-up of a phase 1/2 study

We previously demonstrated that yttrium-90 (Y-90) ibritumomab tiuxetan (Zevalin) radioimmunotherapy (RIT) was safe and effective for relapsed or refractory CD20+, B-cell, non-Hodgkin lymphoma (NHL). We now provide long-term follow-up data in responding patients based on International Workshop Response Criteria. Complete (CR), CR unconfirmed (CRu), and partial response (PR) rates were 29%, 22%, and 22%, respectively (overall response rate 73%, 51% in CR/CRu). Mean time to progression (TTP) and duration of response (DR) in responders were 12.6 months and 11.7 months, respectively. At the maximum tolerated dose (0.4 mCi/kg [14.8 MBq/kg]), TTP and DR in complete responders (CR/CRu) were 28.3 and 27.5 months, respectively. Nine patients (24% of responding patients) had a TTP of more than 3 years. Long-term responders (> 5 years) have been identified. Ibritumomab tiuxetan produces durable responses in patients with indolent and diffuse large B-cell lymphoma. (Blood. 2004;103:4429-4431)

A Phase I dose-escalation study of sibrotuzumab in patients with advanced or metastatic fibroblast activation protein-positive cancer

PURPOSE

The purpose of this research was to determine the safety, immunogenicity, pharmacokinetics, biodistribution, and tumor uptake of repeat infusions of a complementarity-determining region grafted humanized antibody (sibrotuzumab) directed against human fibroblast activation protein (FAP).

EXPERIMENTAL DESIGN

A Phase I open-label dose escalation study was conducted in patients with cancers epidemiologically known to be FAP positive. Patients were entered into one of four dosage tiers of 5, 10, 25, or 50 mg/m(2) sibrotuzumab, administered weekly for 12 weeks, with trace labeling with 8-10 mCi of (131)I in weeks 1, 5, and 9.

RESULTS

A total of 26 patients were entered into the trial (15 males and 11 females; mean age, 59.9 years; age range, 41-81 years). Twenty patients had colorectal carcinoma, and 6 patients had non-small cell lung cancer. A total of 218 infusions of sibrotuzumab were administered during the first 12 weeks of the study, with 24 patients being evaluable. One patient received an additional 96 infusions on continued-use phase for a total of 108 infusions over a 2-year period, and 1 patient received an additional 6 infusions on continued use. There were no objective tumor responses. Only one episode of dose-limiting toxicity was observed. Therefore, a maximum tolerated dose was not reached. Treatment-related adverse events were observed in 6 patients during the infusional monitoring period. Four of the 6 patients, 3 of whom had associated positive serum human antihuman antibody, were removed from the study because of clinical immune responses. Gamma camera images of [(131)I]sibrotuzumab demonstrated no normal organ uptake of sibrotuzumab, with tumor uptake evident within 24-48 h after infusion. Analysis of pharmacokinetics demonstrated a similar mean terminal t(1/2) of 1.4-2.6 days at the 5, 10, and 25 mg/m(2) dose levels, and with a longer mean t(1/2) of 4.9 days at the 50 mg/m(2) dose level.

CONCLUSION

Repeat infusions of the humanized anti-FAP antibody sibrotuzumab can be administered safely to patients with advanced FAP-positive cancer.

Cellular and antibody responses directed against the HIV-1 principal neutralizing domain in HIV-1-infected children

The principal neutralizing domain (PND) for antibody response is located within the V3 variable region of gp120 and can also stimulate T-cell responses. In some adults infected with human immunodeficiency virus (HIV) an HIV-1-specific T-cell response can be detected by demonstrating in vitro proliferation to HIV-1 proteins and peptides. In other HIV-1 infected adults an HIV-1-specific T-cell response can involve interleukin 2 (IL-2) secretion in the absence of T-cell proliferation. To elucidate the T-cell responses to PND in children, we examined the proliferative and the IL-2 secretory responses of peripheral blood lymphocytes from 19 HIV-1-infected children toward a peptide which contained a highly conserved sequence of the principal neutralizing domain of HIVMN (PND-MN). Stimulation with PND-MN induced proliferation of lymphocytes from 2 of the children and IL-2 secretion by lymphocytes from 5 of the children. In a 3-month-old infant, the in vitro cellular response to the PND-MN indicated HIV-1 infection prior to the detection p24 antigen in her serum. Although antibodies directed against PND-MN were detected in all but one of the children examined, the presence of high-affinity/avidity antibodies to the PND-MN correlated with the presence of a cellular response to PND-MN. Thus, in HIV-1-infected children an HIV-1 specific T-cell response in the absence of a proliferative response can be assessed by determination of the IL-2 secretory response and correlates with the generation of high-affinity/avidity antibodies.

Purification and characterization of the epitectin from human laryngeal carcinoma cells

The purification and partial characterization of epitectin (previously called Ca antigen) from a human cancer cell line is described. This glycoprotein, which is expressed on a wide range of human tumors and certain specialized normal epithelia, can be detected using monoclonal antibodies, Ca1, Ca2, and Ca3. The purified glycoprotein had a high density (1.40 g/ml) on isopycnic centrifugation indicating a high carbohydrate content. The molecular mass of epitectin as determined by size-exclusion chromatography ranged from 1.0 to 1.5 x 10(6) daltons. However, the purified epitectin gave two bands of apparent molecular weight 390,000 and 350,000 on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The isoelectric points of epitectin and asialoepitectin were found to be 5.3-5.4 and 6.8, respectively. The oligosaccharides were isolated from metabolically labeled epitectin by alkaline borohydride treatment and their structures established based on high performance liquid chromatography and paper electrophoretic migration, sugar composition, the results of sequential exoglycosidase treatment, periodate oxidation, and methylation analysis. The structures of the three major fractions, which together account for about 80% of the radioactivity, were assigned as NeuNAc alpha 2----3Gal beta 1----(NeuNAc alpha 2----6)3GalNAc(OH), NeuNAc alpha 2----3Gal beta 1----3GalNAc(OH), and Gal beta 1----3 GalNAc(OH). The structures of the minor fractions were tentatively assigned as NeuNAc----Gal(NeuNAc----Gal----GlcNAc)----GalNAc(OH), Gal beta 1----(NeuNAc alpha 2----6)3GalNAc(OH), NeuNAc alpha 2----6GalNAc(OH), and GalNAc(OH). It is proposed that the protein sequence and/or the distribution of the saccharides on the protein core are the determinants on epitectin that are recognized by the Ca antibodies.

Steroid action on gene expression: possible roles of regulatory genes and nuclear acceptor sites

There has been exciting progress in the understanding of the mechanism of action of steroid hormones. The structures and functions of the various receptor protein domains as well as the various domains of steroid-regulated genes, including steroid response elements, are currently being elucidated. The roles of transcription factors in the steroid-altered regulation of gene transcription are just being defined. The nature of the nuclear acceptor sites, i.e. nuclear-binding sites, for steroid receptors are under investigation. The composition, location, and function of these nuclear acceptor sites for steroid receptors is crucial for understanding the mechanism of steroid regulation of gene expression. Possible roles of specific, DNA-binding, chromatin proteins in these acceptor sites have been suggested. A very rapid action of steroids on the expression of proto-oncogenes that code for nuclear regulatory proteins has recently been described. Using this information, we have proposed a novel steroid action model utilizing "regulatory genes" whereby the steroids would rapidly alter the expression of regulatory genes (early genes) whose protein products would return to the nucleus to regulate the expression of structural genes (late genes). The latter would occur via binding of these regulatory proteins (e.g. transcription factors) to the steroid-regulatory elements neighboring these late genes. This model would explain many of the characteristics reported from many laboratories on the action of steroid hormones on gene expression.

Electron-microscopic studies of the CA antigen, epitectin

Epitectin, the mucin-like glycoprotein defined by the monoclonal antibodies CA1, CA2 and CA3, has been examined by electron microscopy to determine its shape and size. It appears to be a single extended strand with a mean length of about 270 nm. The antibodies CA1 and CA2 appear to bind preferentially to a terminal site on the epitectin molecule.

Detection of the urinary 'PUM' polymorphism by the tumour-binding monoclonal antibodies Ca1, Ca2, Ca3, HMFG1, and HMFG2

A series of human urinary mucin-like glycoproteins, previously detected using lectins to stain gels after electrophoresis, and showing genetic polymorphism (Karlsson et al., 1983) can also be detected using the tumour-binding monoclonal antibodies, Ca1, Ca2, Ca3, HMFG1, and HMFG2. The evidence from immunoprecipitation and immunoadsorbant chromatography experiments is that the epitopes recognized by these antibodies are carried on the same molecules as the lectin-binding determinants. The discovery that the antibodies bind specifically to a family of molecules which show genetic polymorphism provides a powerful new tool for the analysis of the material expressed aberrantly in cancer.

Ca2 and Ca3. New monoclonal antibodies evaluated as tumor markers in serous effusions

Ca2 and Ca3 are new monoclonal antibodies of IgG1 class, directed against the Ca antigen, a mucus-type glycoprotein expressed on the surface of a wide range of malignant human cells and certain specialized normal epithelia. These antibodies were produced by immunization with purified preparations of the Ca antigen. They were tested to assess their value in the diagnosis of malignant effusions. Immuno-alkaline-phosphatase staining was used. Smears of pleural and peritoneal effusions were chosen to show: undoubted malignant cells of various types; and mesothelial cells in effusions from cases in which cancer was not in question. The Ca2 antibody, at 1 in 20 dilution of the culture supernatant, was the most specific, giving no reactions with benign mesothelial cells from any of the 35 cases tested. Malignant cells were clearly stained in 35 of 40 cases of carcinoma or mesothelioma. The staining was negative in two cases of oat cell bronchial carcinoma, and in three of four cases of carcinoma of the colon. Ca3 gave similar, but somewhat stronger, reactions with carcinoma cells, but was less specific, reacting weakly with mesothelial cells in 8 of 35 benign effusions. Because the false-negative reactions given by the Ca series of antibodies are to some extent complementary to those given by monoclonal antibodies directed against the carcinoembryonic antigen (CEA), a combination of Ca2 and anti-CEA is recommended as a most useful addition to the normal cytologic examination of effusions.

Sites of dipeptide hydrolysis in relation to sites of histidine and glucose active transport in hamster intestine

The effects of dipeptides and amino acids on the active transport of L-histidine and D-glucose by sacs of everted small intestine of the hamster have been used to determine the sites of final hydrolysis of the dipeptides in relation to the sites of active transport of L-histidine and D-glucose. The results, plus earlier observations (Wiseman, 1977), show that (a) dipeptide active transport occurs at a superficial site, followed by progressively deeper sites for (b) final hydrolysis of glycyl-phenylalanine and phenylalanyl-glycine, then deeper (c) L-histidine active transport, then (d) final hydrolysis of alanyl-alanine, alanyl-leucine, glycyl-alanine, glycyl-proline, leucyl-alanine and leucyl-leucine, then (e) D-glucose active transport, then (f) final hydrolysis of alanyl-glycine, alanyl-valine, glycyl-glycine, prolyl-glycine, valyl-alanine and valyl-valine. The site of D-glucose active transport (2e) and all the sites superficial to it (2a-d) lie in the intestinal epithelial cell's brush-border. The location within the cell of site(s) 2f is not known; it may lie in the cytosol. All the dipeptides appeared to inhibit L-histidine active transport by the release of free amino acid and not by action of intact dipeptide, supporting the view that dipeptides and free amino acids do not share a common transport pathway in the epithelium of the small intestine.

Structure and function of the Ca antigen

The Ca antigen, which can be detected in a wide range of malignant human tumours by means of the Cal antibody, is a glycoprotein of the mucin type. At least 95% of the carbohydrate is 0-glycosidically linked to the polypeptide which contains high proportions of glycine, serine and glutamic acid. The carbohydrate has a very simple structure: it is composed almost entirely of tetra- tri- and disaccharides having the general formula (NeuNac)n leads to [Gal leads to GalNac] alpha leads to, where n = 0, 1 or 2. In many malignant cell lines, the antigen is produced constitutively in vitro; but in one that has been examined, its synthesis can be induced by high concentrations of lactate. Evidence is presented for the view that a primary function of this glycoprotein is to shield the cells that produce it from hydrogen ion concentrations outside of the physiological range. The presence of the Ca antigen in malignant tumours may thus be a reflection of metabolic conditions that are known to be characteristics of such tumours.

Lipid intermediate in the synthesis of the linkage unit that joins teichoic acid to peptidoglycan in Bacillus subtilis

Membranes from Bacillus subtilis W23 synthesized a lipid precursor of the linkage unit that attaches teichoic acid to the cell wall. It contained glycerophosphoryl-N-acetylglucosamine, linked through an acid-labile bond to a lipid.

Site of intestinal dipeptide hydrolysis

1. Sacs of everted small intestine of the hamster have been used to study the site of final hydrolysis of twelve dipeptides. 2. The results suggest that L-alanyl-glycine, glycyl-glycine, L-valyl-L-valine, L-alanyl-L-valine, L-valyl-L-alanine and L-prolyl-glycine are hydrolysed beyond the locus of the active transport mechanism for D-glucose, perhaps even within the cell. These may be designated class 1 (deep) dipeptides. 3. In contrast, superficial (perhaps even surface) hydrolysis seems to occur with L-alanyl-L-alanine, L-leucly-L-leucine, glycyl-L-alanine, L-alanyl-L-leucine, L-leucyl-L-alanine and glycyl-L-proline. These may be designated class 2 (superficial) dipeptides. 4. All the dipeptides were able to partially inhibit D-glucose active transport, the findings supporting the view that more than one mechanism may exist for the active absorption of the sugar.

The use of dietary-restricted rat intestine for active transport studies

1. The effect of dietary restriction (sufficient to produce a loss of about 32% of initial body weight) on intestinal active transport has been studied in the rat by the use of sacs of everted mid-small intestine. Eight D-sugars, four L-sugars and two D-amino acids were employed.2. Dietary restriction enhanced the normally occurring active transport of D-galactose, 3-O-methyl-D-glucose and D-methionine. In addition, sacs of dietary-restricted small intestine were able to concentrate in the serosal fluid D-fucose, D-xylose and D-histidine, which sacs of normal rat intestine could not do. The final (1 hr) serosal/mucosal concentration ratios produced for these actively transported substances were independent of net water movement.3. Sugars which were not concentrated in the serosal fluid of sacs of fully fed or dietary-restricted intestine were D-arabinose, D-fructose, D-glucosamine, D-mannose, L-arabinose, L-fucose, L-sorbose and L-xylose.4. The characteristics of D-fucose and D-xylose active transport suggest that they are transported by the mechanism which actively transports D-glucose. The comparatively low content of D-glucose in dietary-restricted intestine, compared with fully fed intestine, may be part of the explanation for observable active transport of D-fucose and D-xylose by dietary-restricted sacs.5. Thinning of the intestinal wall is believed not to be the cause of the enhanced active transport found during dietary restriction.6. The results show that dietary-restricted rat small intestine may, at times, be more useful than fully fed rat small intestine in the study of intestinal active transport.

Active transport of L-glucose by isolated small intestine of the dietary-restricted rat

1. The effect of semistarvation and complete starvation (sufficient to produce a loss of about 32 and 25% respectively of initial body weight) on the active transport of L-glucose has been studied by the use of sacs of everted mid-small intestine of rats. The animals were allowed free access to water.2. Sacs from animals on a restricted diet transported L-glucose against its concentration gradient, but sacs from fully fed rats did not. Even when sacs from fully fed rats were distended sufficiently to cause them to lose serosal volume, the L-glucose concentration in the final serosal fluid was never greater than that in the final mucosal fluid.3. The L-glucose active transport was independent of net water movement, needed oxygen, was not demonstrable at 27 degrees C, and required Na ions at a concentration of 83 mM or greater. It could be completely inhibited by 10(-6)M phlorrhizin, or 10 mM L-histidine, or 1.39 mM D-glucose. Phlorrhizin at a concentration of 10(-8)M reduced, but did not prevent, L-glucose active transport.4. It seems probable that L-glucose active transport is mediated by the mechanism that actively transports D-glucose.5. Un-incubated mid-small intestine of fully fed rats contained 37.8 mg D-glucose/100 g wet wt. of tissue, whereas semistarved intestine had only 10.8 mg D-glucose/100 g. The lack of demonstrable active transport of L-glucose by normal intestine may possibly have been caused, at least in part, by inhibition of the process by endogenous D-glucose.6. There appeared to be no metabolism of L-glucose by rat intestine, nor conversion to the D-form.7. The hypothesis that sugars require the D-pyranose ring structure for active absorption is no longer tenable.

Studies on the active transport of D-glucose and L-histidine by rats and golden hamsters fed on a penicillin-enriched diet

1. The effect of a penicillin-enriched diet (100 mg or 1000 mg penicillin-G/kg food) on the active transport of D-glucose and L-histidine has been investigated by the use of sacs of everted small intestine of normal young adult rats and golden hamsters. The antibiotic was given for up to several weeks.

2. The penicillin made no difference to the final concentration gradients of D-glucose or L-histidine achieved by rat small intestine, although with the hamster these appeared somewhat improved. Water entry into the serosal fluid remained unchanged.

3. The lengths and the dry weights of the small intestines of both species were not altered by the dietary regimen.

Further studies on intestinal active transport during semistarvation

1. The effect of semistarvation (sufficient to produce a loss of 18-28% of initial body weight) on the active transport of D-glucose and L-histidine by the rat, the guinea-pig and the golden hamster has been investigated by the use of sacs of everted small intestine (from upper jejunum to lower ileum).2. In the rat and the guinea-pig the dietary restriction resulted in increased active transport in all regions of the small intestine. In contrast, it caused no alteration in active transport in the hamster.3. The response in the rat was most impressive in the middle-to-lower ileum during D-glucose uptake. Whereas normal sacs from this area appeared unable to move the sugar against its concentration gradient, sacs from semistarved rats did so quite well.4. Although there was a considerable loss (24-29%) of intestinal dry weight in all three species when the food intake was reduced, shortening of the small intestine was not detectable in the guinea-pig or the hamster and was present to only a minor extent in the rat.5. Evidence is presented indicating that the enhanced active transport is not merely a reflexion of the thinning of the intestinal wall and that it occurs during complete as well as in partial starvation.

Effect of amino acids on sugar absorption

1. Sacs of everted mid-small intestine of the hamster have been used to study the effect of amino acids on sugar absorption.2. The sugars employed were D-glucose, D-galactose, 3-O-methyl-D-glucose, D-fucose, L-glucose, alpha-glucoheptose, L-fucose, D-mannose and L-sorbose. The amino acids were L- and D-histidine, L- and D-methionine, L- and D-alanine, L- and D-valine, L- and D-glutamic acid, L-leucine, L-proline, L-ornithine and L-aspartic acid.3. Actively absorbed amino acids considerably inhibit the transport of actively absorbed sugars. The results give support for the view that D-histidine and L-glucose are actively transferred. Passively absorbed amino acids and sugars are not involved.4. As L-glutamic and L-aspartic acids in the mucosal fluid have no inhibitory effect on D-glucose absorption, although mucosal fluid L-alanine is quite potent, the step at which the latter exerts its inhibitory action must be before that at which the intracellular transamination of L-glutamic and L-aspartic acids occurs. It would seem likely, therefore, that L-alanine interferes with the process by which epithelial cells capture and concentrate sugars at the luminal border.5. More than one active transfer system may exist for D-glucose.6. The influence of actively absorbed L-amino acids on D-glucose active transport seems to be in some way related to the efficiency with which the amino acids are themselves concentrated.7. Inhibition of D-glucose active absorption by an amino acid may be a simple test of an amino acid's participation in an active transport system.