Randomized clinical trial of glutamine-supplemented versus standard parenteral nutrition in infants with surgical gastrointestinal disease.

BACKGROUND: Addition of glutamine to parenteral nutrition in surgical infants remains controversial. The aim of this trial was to determine whether glutamine supplementation of parenteral nutrition in infants requiring surgery would reduce the time to full enteral feeding and/or decrease the incidence of sepsis and septicaemia. METHODS: A prospective double-blind multicentre randomized clinical trial was performed in surgical infants less than 3 months old who required parenteral nutrition. Patients were allocated to treatment or control groups by means of minimization. Infants received either 0·6 g per kg per day alanyl-glutamine (treatment group) or isonitrogenous isocaloric parenteral nutrition (control group) until full enteral feeding was achieved. Primary outcomes were time to full enteral feeding and incidence of sepsis. Cox regression analysis was used to compare time to full enteral feeding, and to calculate risk of sepsis/septicaemia. RESULTS: A total of 174 patients were randomized, of whom 164 completed the trial and were analysed (82 in each group). There was no difference in time to full enteral feeding or time to first enteral feeding between groups, and supplementation with glutamine had no effect on the overall incidence of sepsis or septicaemia. However, during total parenteral nutrition (before the first enteral feed), glutamine administration was associated with a significantly decreased risk of developing sepsis (hazard ratio 0·33, 95 per cent confidence interval 0·15 to 0·72; P = 0·005). CONCLUSION: Glutamine supplementation during parenteral nutrition did not reduce the incidence of sepsis in surgical infants with gastrointestinal disease. REGISTRATION NUMBER: ISRCTN83168963 (http://www.controlled-trials.com).

Isolation and characterization of a factor from calf serum that promotes the pigmentation of embryonic and transformed melanocytes.

A protein (Mr = 63,000) from calf serum that promotes the pigmentation of cultured chick neural crest and mouse melanoma cells has been partially isolated and characterized in this study. The stimulation of melanin synthesis in cultured cells was used to follow its activity during purification. The pigment-promoting factor was isolated by sequential column chromatography on dye-agarose matrices followed by hydroxyapatite and high pressure molecular sieve chromatography. The factor was found to stimulate melanin biosynthesis at 2-4 micrograms/ml and was specific for melanin-producing cells and their precursors. Antibodies raised in rabbits against the factor inhibited its pigment-promoting activity as well as that of whole calf serum. Enzyme-linked immunoadsorbent assays demonstrated that calf and bovine sera contain molecules that cross-react with the pigment-promoting factor. Horse, human, rat, and chicken sera, which lack the biological activity, also lacked immunological cross-reactivity. Extracts of certain tissues, particularly the submaxillary gland, were observed to be rich sources of pigment-promoting activity.

Retinoid X receptor (RXR) within the RXR-retinoic acid receptor heterodimer binds its ligand and enhances retinoid-dependent gene expression.

Retinoic acid receptor (RAR) and retinoid X receptor (RXR) form heterodimers and regulate retinoid-mediated gene expression. We studied binding of RXR- and RAR-selective ligands to the RXR-RAR heterodimer and subsequent transcription. In limited proteolysis analyses, both RXR and RAR in the heterodimer bound their respective ligands and underwent a conformational change in the presence of a retinoic acid-responsive element. In reporter analyses, the RAR ligand (but not the RXR ligand), when added singly, activated transcription, but coaddition of the two ligands led to synergistic activation of transcription. This activation required the AF-2 domain of both RXR and RAR. Genomic footprinting analysis was performed with P19 embryonal carcinoma cells, in which transcription of the RARbeta gene is induced upon retinoid addition. Paralleling the reporter activation data, only the RAR ligand induced in vivo occupancy of the RARbeta2 promoter when added singly. However, at suboptimal concentrations of RAR ligand, coaddition of the RXR ligand increased the stability of promoter occupancy. Thus, liganded RXR and RAR both participate in transcription. Finally, when these ligands were tested for teratogenic effects on zebra fish and Xenopus embryos, we found that coadministration of the RXR and RAR ligands caused more severe abnormalities in these embryos than either ligand alone, providing biological support for the synergistic action of the two ligands.

Evidence against a role for a pertussis toxin-sensitive G protein in Ca2+ mobilization in rat parotid acinar cells.

Hormone-induced Ca2+ mobilization in rat parotid acinar cells is reportedly mediated via an as yet uncharacterized G protein. We have studied the sensitivity to pertussis toxin (PTx) of this signal transduction mechanism. When rats were treated with Ptx (1.3-1.5 micrograms per animal) for 72 h, a 41 kDa membrane protein was ADP-ribosylated. This PTx treatment regimen, also, resulted in a more than 80% block of the ability of the muscarinic agonist carbachol to inhibit beta-adrenergic receptor-stimulated parotid adenylyl cyclase activity. However, cytosolic Ca2+ levels, in response to either carbachol or AIF-4, were comparable in cells prepared from both untreated or PTx-treated rats, when incubated either in the absence or presence of extracellular Ca2+. Further, both the sensitivity of the Ca2+ response to carbachol and the ability of the agonist-sensitive intracellular Ca2+ stores to be refilled by extracellular Ca2+ were unaffected by PTx treatment. Parotid membranes also contained three low-molecular-weight GTP-binding proteins (25, 22 and 18 kDa) which were unaffected by PTx. These results show that there is only one detectable substrate in parotid membranes for a PTx-catalyzed ADP-ribosylation and that hormone-induced Ca2+ mobilization events in parotid acinar cells are not mediated via PTx-sensitive components.

High affinity quinuclidinyl benzilate binding to rat parotid membranes requires muscarinic receptor. G protein interactions.

The binding of the non-selective muscarinic antagonist [3H]quinuclidinyl benzilate (QNB) to rat parotid membranes was characterized. Under equilibrium conditions, [3H]QNB bound to a homogenous population of muscarinic receptors (Kd, 118 +/- 19 pM; Bmax, 572 +/- 42 fmol/mg membrane protein, n = 12). The addition of G protein activators AlF4- or guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S) + Mg2+ increased the Kd by 77 +/- 7% (n = 4, P less than 0.05) and 83 +/- 27% (n = 7, P less than 0.05), respectively, without a change in the Bmax or homogeneity of the binding site. GTP gamma S added without exogenous Mg2+ did not affect [3H]QNB binding. Thus, optimal QNB binding requires a muscarinic receptor/G protein interaction.

Evidence for the convergence of beta-adrenergic and muscarinic signalling systems at a post-receptor site.

The beta-adrenergic agonist isoproterenol stimulates inositol trisphosphate (IP3) formation and cytosolic Ca2+ [( Ca2+]i) mobilization in rat parotid acini via a cAMP-dependent process. Atropine, a muscarinic antagonist, inhibited these isoproterenol responses without affecting isoproterenol-induced amylase secretion or peak [Ca2+]i and IP3 responses elicited by alpha 1-adrenergic stimulation with epinephrine. Atropine had no effect on isoproterenol-induced [Ca2+]i responses in a cell line which lacked muscarinic receptors and did not alter beta-adrenoreceptor ligand binding. These results suggest that the inhibition by atropine results from a post-receptor effect on cAMP-mediated stimulation of phosphatidylinositol 4,5 bisphosphate (PIP2) hydrolysis.

Disposition and tissue distribution of boron after infusion of borocaptate sodium in patients with malignant brain tumors.

PURPOSE: In the frame of the Czech boron neutron capture therapy (BNCT) project, a clinical Phase I study of borocaptate sodium [Na2B12H11SH (BSH)] as the boron-10 delivery agent was performed to obtain data on disposition and tissue distribution of boron after an infusion of this compound, as well as to establish an optimal protocol for BNCT of malignant cerebral tumors. METHODS AND MATERIALS: The kinetics of boron disposition after an infusion of borocaptate sodium (25 mg/kg body wt over the period of 1 h) was studied in a group of 10 patients with astrocytoma or glioblastoma of cerebral hemispheres using a modification of the Soloway-Messer colorimetric method. The boron content of tissues (tumor, healthy brain, dura mater, muscle, skin, and cranial bone) removed during the operation performed with latencies varying between 3 and 18 h was investigated by atomic emission spectrometry. RESULTS: Compartmental analysis of boron blood concentrations has shown that in the majority of patients (four males and three females), the concentration decline can be adequately described by a two-compartment pharmacokinetic model (i.e., by a biexponential relationship). The calculated half-lives of the initial (fast) phase of the concentration decline varied between 0.85 and 3.65 h, whereas the half-life values for the terminal (slow) phase ranged between 22.2 and 111.8 h. However, in the remaining three patients (all females), the goodness of fit of the boron concentration data was significantly better when a pharmacokinetic model with three compartments was assumed. In these patients, therefore, an additional ultrafast phase with a half-life varying between 17 and 37 min was detected in the beginning of the boron blood concentration decline. On the other hand, in one of these patients, the half-life of the terminal phase was found to be 415 h (i.e., more than 17 days). Such a long persistence in the body is explained by the very high value of the total distribution volume, indicating extensive binding of BSH in peripheral tissues. Another reason may be enterohepatic recycling of BSH. CONCLUSION: Tumor-to-blood ratios higher than 1.5, which are necessary for an effective outcome of BNCT, can be obtained only if the time interval elapsing between the onset of surgery and termination of BSH infusion is at least 12 h.

Immunohistochemical localization of fibronectin and chondronectin in canine articular cartilage.

We compared the distribution of fibronectin and chondronectin within the matrix of canine articular cartilage. Fibronectin was found throughout the matrix as well as pericellularly. In contrast, chondronectin was observed predominantly associated with the cell or pericellular matrix. Interactions of these molecules with matrix components in the pericellular matrix probably differs, however, since concentrations of hyaluronidase which prevented detection of pericellular fibronectin allowed detection of chondronectin. Chondronectin and fibronectin were detected in osteoarthritic cartilage as well as in disease-free cartilage. Penetration of biotinylated fibronectin into cartilage from the external medium occurred only in osteoarthritic cartilage and proceeded only from the articular surface. Disease-free cartilage appeared to maintain a barrier to fibronectin penetration from the articular surface which was sustained even after the proteoglycan content was markedly depleted by incubation of cartilage with catabolin or lipopolysaccharide. In cartilage that was proteoglycan-depleted, the only detectable penetration of external fibronectin was from the cut surface.

Submaximal exercise testing after acute myocardial infarction: myocardial scintigraphic and electrocardiographic observations.

The relation between global and regional left ventricular function and electrocardiographic signs of ischemia at rest and during submaximal supine exercise was studied in 27 patients 2 to 3 weeks after acute myocardial infarction. Dynamic myocardial scintigraphy was performed at rest and during submaximal exercise utilizing an in vivo method of labeling red blood cells with technetium-99m pertechnetate. Gated radionuclide blood pool scintigrams were obtained in a modified left anterior oblique, and in some patients also in the right anterior oblique projection, to measure left ventricular ejection fraction and segmental wall motion. Electrocardiographic monitoring of heart rate and rhythm was provided during the exercise. The submaximal exercise test was terminated when the patient's heart rate reached 125 beats/min or if angina, malignant ventricular ectopy or electrocardiographic evidence of myocardial ischemia developed before this rate was reached. The data demonstrate that patients with a recent anterior myocardial infarct, in contrast to patients with a recent inferior or nontransmural infarct, manifest a significant reduction in left ventricular ejection fraction with submaximal exercise. Of the eight patients with an anterior infarct, seven had segmental wall motion abnormalities at rest. Four of these eight manifested more severe abnormalities with submaximal exercise; three had abnormalities at rest that did not change with exercise. Four of the eight had a positive electrocardiographic response during exercise (two were taking digoxin). Of these four, only two had more marked wall motion abnormalities with effort. Of the 13 patients with an inferior infarct, 11 had apparently normal wall motion in the modified left anterior oblique projection at rest, including 2 who manifested segmental wall motion abnormalities with submaximal exercise; the 2 remaining patients had wall motion abnormalities at rest that, on exercise, became more marked in one and were unchanged in one. Four of the 13 had a positive electrocardiographic response with exercise (one was taking digoxin); only one of these had a detectably more severe wall motion abnormality with exercise. Of the six patients with a nontransmural infarct, four had no identifiable wall motion abnormalities at rest; in one of these, an abnormality developed with exercise. The remaining two patients had wall motion abnormalities at rest; in one, a positive electrocardiographic ischemic response developed with exercise. Patients with an anterior infarct appear to have a different functional ventricular response to submaximal exercise at the time of hospital discharge than patients with an inferior or nontransmural infarct. To identify ischemic responses with submaximal exercise in these patients one should ideally use both electrocardiographic monitoring and dynamic myocardial scintigraphy.

Triple-drug immunosuppression with steroid discontinuation by six months after heart transplantation.

BACKGROUND: Triple-drug immunosuppression with cyclosporine, azathioprine, and prednisone is associated with complications which might be reduced by steroid withdrawal. METHODS: In two groups of heart transplant recipients maintained on an identical regimen of cyclosporine and azathioprine, prednisone was withdrawn in group I patients (n = 35) by 6 months after transplantation, whereas in group II patients (n = 49) prednisone was never discontinued. RESULTS: Survival was similar in the two groups. The incidence of acute graft rejection was significantly higher in group I (54%) than in group II (12%), whereas infective complications were significantly lower in group I than in group II (0.63 versus 1.02 episode/patient). The degree of posttransplantation weight gain, lipid abnormalities, and incidence of hypertension were not modified by the fast tapering of prednisone, whereas the incidence of cataract and compression fracture and the degree of bone loss were significantly reduced in group I. Graft function and incidence of coronary artery disease were similar in the two groups. CONCLUSIONS: The present data suggest that prednisone can be safely withdrawn in heart transplant recipients without jeopardizing survival and graft function. Longer follow-up is needed to assess the full impact of early withdrawal of steroids from triple-drug immunosuppression, especially on long-term graft function and incidence of coronary artery disease. Benefits of early steroid withdrawal included a reduction in bone loss, which might ultimately have a major positive impact on the extent of long-term rehabilitation and exercise tolerance after heart transplantation.

Differential reflex control of forearm and calf resistance vessels by chemosensitive cardiac afferent activation.

The aim of this study was to determine whether chemosensitive ventricular afferent activation in humans evokes a diffuse pattern of reflex vasodilation involving the skeletal muscle circulation of all the extremities or a highly specified pattern of vasodilation that is limited to the rather small vascular bed of the forearm. In 10 patients with innervated ventricles and 7 patients with denervated ventricles resulting from heart transplantation, we performed simultaneous plethysmographic recordings of blood flow in the forearm and calf during chemosensitive ventricular afferent activation with intracoronary Renografin. In patients with innervated ventricles, intracoronary Renografin evoked directionally opposite vascular responses in the forearm and calf: forearm resistance decreased from 50 +/- 11 to 31 +/- 8 units, whereas calf resistance increased from 42 +/- 7 to 59 +/- 9 units (P < 0.05, calf vs. forearm). Forearm vasodilation was eliminated after heart transplantation, indicating that this is a reflex response caused by ventricular afferents. In contrast, calf vasoconstriction was well preserved despite ventricular deafferentation, indicating that this response is caused by mechanisms other than ventricular afferent activation, possibly the sinoaortic baroreceptors. Taken together, these findings document a remarkable degree of specificity in the effects of cardiac afferent activation on the reflex regulation of regional vasomotor tone in humans.

Successful surgical repair of aortic dissection presenting with complete heart block.

Acute dissection of the ascending aorta can present with complete heart block if the dissecting hematoma involves the interatrial septum near the atrioventricular node. We report a case of acute type A dissection presenting with complete heart block treated with emergency grafting of the ascending aorta, aortic valve replacement, and coronary artery bypass grafting. The patient survived, although complete heart block persisted requiring permanent pacemaker implantation.

Acute infective endocarditis.

Acute infective endocarditis is an important cardiovascular emergency that can be detected with improved diagnostic techniques. In the last few decades we have witnessed a changing spectrum of microorganisms causing infective endocarditis. Successful treatment of infective endocarditis is enhanced by the combined and cooperative efforts of the internist and the surgeon. In this article, we have discussed the clinical evaluation, laboratory techniques, and noninvasive studies by which proper diagnosis can be made and appropriate antimicrobial therapy instituted. We have also reviewed the indications for surgical intervention. With careful clinical evaluation and proper application of the diagnostic and therapeutic modalities, acute infective endocarditis can often be cured.

Response of rat salivary glands to mastication of pelleted vitamin A-deficient diet.

Interpretation of previous studies of the effects of hypovitaminosis. A on salivary glands is confounded by the atrophic effects of liquid or powdered diets. The purpose of this study was to reevaluate the effects of vitamin. A deficiency on the morphology and function of rat salivary glands using a pelleted diet that promotes physiological levels of masticatory stimulation. Profound vitamin A deficiency resulted in a marked decrease in stimulated parotid secretion. Histological evaluation demonstrated the development of squamous metaplasia in the ducts of parotid, submandibular and sublingual salivary glands; however, atrophy was observed only in serious salivary glands. In the parotid gland the degree of atrophy corresponded to the decrease in stimulated secretion. Mild hypovitaminosis A (before the development of squamous metaplasia in ducts) was associated with distinctly different effects. The parotid gland was moderately enlarged. There was also a significant increase in stimulated secretion, which was not explained by changes in gland size, muscarinic receptor number or affinity, or receptor-mediated calcium signalling.

Appendicular skeletal tumours coined by odontogenic terms.

Two intriguing tumours in the appendicular skeleton are coined by odontogenic terms: the "adamantinomas" and "cementomas" (or "cementifying fibromas"). Both are extremely rare, mainly the latter. Eight verified observations are presented here: five adamantinomas and three cementomas. Whereas in adamantinomas, the localization and radiographic picture was very typical in all cases, only one cementoma was found in the metaphysis of a long tubular bone in our survey. Diaphyseal tibial localization in one, and metacarpal in the another patient are the first two atypical localizations, described for this tumor in the world's medical literature. Angiography is characteristic for a benign expansive lesion and should be carried out in all cases. An "en bloc" resection is the intervention of choice for both these entities.

Kidney function changes in rats after single-dose administration of borocaptate sodium.

Kidney function changes after single-dose administration of borocaptate sodium (mercaptoundecahydro-closododecaborate, B12H11SH, BSH) were studied in rats. Changes of glomerular filtration rate (GFR) measured as 14C-inulin clearance, renal plasma flow rate (3H-p-aminohippuric acid clearance) and urine flow rate (UFR) after a slow intravenous injection of BSH (25 mg/kg b.w.) were investigated in rats under pentobarbital anaesthesia. It was found that a slow BSH injection induces a gradual decrease of renal plasma flow and glomerular filtration rate resulting in an almost constant reduction of the filtration fraction. These alterations were accompanied by a temporary increase of urine flow rate. Although a direct effect of BSH on the nephron cannot be excluded, it is suggested that the observed changes in kidney function might at least partly be mediated by disturbances in the function of the cardiovascular system following BSH injection. The role of the dianionic sulfhydryl group present in the borocaptate molecule in inducing these renal functional changes is discussed.

A comparison of mathematical models for estimating right ventricular volumes in animals and man.

Volume of 19 right ventricular canine casts and 11 right ventricular human casts were obtained by water displacement and compared to three different mathematical models for estimating right ventricular volumes by biplane cineangiography. In the canine studies, significant linear correlation coefficients were obtained using the longest measured length method (r = 0.92), the triangular modification of Simpson's rule (r = 0.93), and the elliptical modification of Simpson's rule (r = 0.93). The human studies resulted in similar significant correlation coefficients of 0.96, 0.97, and 0.97, respectively. Although the highest correlation with the lowest standard error of estimate was obtained using the triangular model, all three mathematical models produced volume estimations that feel within acceptabe biological limits of accuracy.

The in vitro effect of sodium mercaptoundecahydrododecaborate (borocaptate) on sulfhydryl groups of different rat tissues.

The effect of borocaptate on structural protein sulfhydryl (SH) groups of different organs and kidney subcellular fractions was studied in vitro. It was shown that the binding capacity of borocaptate is not the same for different tissues and subcellular fractions. The highest binding capacity was in the liver, while kidney and brain values were significantly lower. Therefore, it appears that the same concentration of borocaptate may have different effects in various organs.

The diuretic effect of borocaptate sodium in rats and in patients with brain tumors.

Kidney function changes after single-dose administration of borocaptate sodium were studied in rats and in patients with brain tumors. Changes of glomerular filtration rate (GFR) measured as 14C-inulin clearance and urine flow rate (UFR) after a slow intravenous injection of BSH (25 and 50 mg/kg b.w., respectively) were investigated in rats under pentobarbital anesthesia. The effect of BSH has been compared with that of its disulfide (BSSB) which is spontaneously generated by oxidation of BSH during storage. It was found that BSH decreases GFR in relation to dose and, in the same way, causes a temporary increase of UFR. On the other hand, BSSB (50 mg/kg) induced a large reversible decrease of GFR as well as a decrease of urine excretion. Measurements of GFR (inulin clearance), renal plasma flow (PAH clearance) and urine excretion were taken in a group of patients with brain tumors in which boron disposition after an infusion of BSH (25 mg/kg b.w. over 1 h) had been studied. An increase in urine production was the dominant effect (up to 200% of the initial value), with the alterations of GFR and RPF being of minor significance except in one patient with a GFR reduction up to almost 50% the original value. Kidney function changes after BSH or BSSB administration are supposedly related to the high retention of BSH in kidney.