Transformation Foci in IDH1-mutated Gliomas Show STAT3 Phosphorylation and Downregulate the Metabolic Enzyme ETNPPL, a Negative Regulator of Glioma Growth.

IDH1-mutated gliomas are slow-growing brain tumours which progress into high-grade gliomas. The early molecular events causing this progression are ill-defined. Previous studies revealed that 20% of these tumours already have transformation foci. These foci offer opportunities to better understand malignant progression. We used immunohistochemistry and high throughput RNA profiling to characterize foci cells. These have higher pSTAT3 staining revealing activation of JAK/STAT signaling. They downregulate RNAs involved in Wnt signaling (DAAM2, SFRP2), EGFR signaling (MLC1), cytoskeleton and cell-cell communication (EZR, GJA1). In addition, foci cells show reduced levels of RNA coding for Ethanolamine-Phosphate Phospho-Lyase (ETNPPL/AGXT2L1), a lipid metabolism enzyme. ETNPPL is involved in the catabolism of phosphoethanolamine implicated in membrane synthesis. We detected ETNPPL protein in glioma cells as well as in astrocytes in the human brain. Its nuclear localization suggests additional roles for this enzyme. ETNPPL expression is inversely correlated to glioma grade and we found no ETNPPL protein in glioblastomas. Overexpression of ETNPPL reduces the growth of glioma stem cells indicating that this enzyme opposes gliomagenesis. Collectively, these results suggest that a combined alteration in membrane lipid metabolism and STAT3 pathway promotes IDH1-mutated glioma malignant progression.

Human factor IX transgenic sheep produced by transfer of nuclei from transfected fetal fibroblasts.

Ovine primary fetal fibroblasts were cotransfected with a neomycin resistance marker gene (neo) and a human coagulation factor IX genomic construct designed for expression of the encoded protein in sheep milk. Two cloned transfectants and a population of neomycin (G418)-resistant cells were used as donors for nuclear transfer to enucleated oocytes. Six transgenic lambs were liveborn: Three produced from cloned cells contained factor IX and neo transgenes, whereas three produced from the uncloned population contained the marker gene only. Somatic cells can therefore be subjected to genetic manipulation in vitro and produce viable animals by nuclear transfer. Production of transgenic sheep by nuclear transfer requires fewer than half the animals needed for pronuclear microinjection.

Deletion of the alpha(1,3)galactosyl transferase (GGTA1) gene and the prion protein (PrP) gene in sheep.

Nuclear transfer offers a cell-based route for producing precise genetic modifications in a range of animal species. Using sheep, we report reproducible targeted gene deletion at two independent loci in fetal fibro-blasts. Vital regions were deleted from the alpha(1,3)galactosyl transferase (GGTA1) gene, which may account for the hyperacute rejection of xenografted organs, and from the prion protein (PrP) gene, which is directly associated with spongiform encephalopathies in humans and animals. Reconstructed embryos were prepared using cultures of targeted or nontargeted donor cells. Eight pregnancies were maintained to term and four PrP-/+ lambs were born. Although three of these perished soon after birth, one survived for 12 days. These data show that lambs carrying targeted gene deletions can be generated by nuclear transfer.

Modifications to improve the efficiency of zona-free mouse nuclear transfer.

In the present study, some modifications were made to the zona-free nuclear transfer technique in the mouse in order to achieve greater efficiency. Firstly, a 1-h interval was allowed between cumulus removal and zona pellucida digestion. Secondly, acid Tyrode's was selected for zona pellucida removal, because contrary to pronase, it allows embryo survival during parthenogenic activation in the absence of calcium. Even when the exposure time to pronase was reduced to as little as 1 min or washed with fetal calf serum to inhibit the enzyme, the percentage of lysis during activation in the absence of calcium was still very high. Thirdly, electrofusion was performed at room temperature (21 degrees C), instead of 30 degrees C as in our previous experiments. Finally, embryos were cultured in groups of 12-15, instead of individually, using a "well of the wells" system during activation and culture. When compared, parthenogenic activated control embryos showed an increase in the development to blastocyst when cultured in pairs instead of individually. By the end of the experiments and using embryonic stem (ES) cells, there was a significant increase in fusion rate (1.5-fold increase) and in development to morula/blastocyst from cleaved reconstructed embryos (1.5-fold increase) when compared with the results before the modifications. A 2.4-fold increase in overall efficiency was achieved from the oocyte to morula/blastocyst stages.

ASCT2/SLC1A5 controls glutamine uptake and tumour growth in triple-negative basal-like breast cancer.

Alanine, serine, cysteine-preferring transporter 2 (ASCT2; SLC1A5) mediates uptake of glutamine, a conditionally essential amino acid in rapidly proliferating tumour cells. Uptake of glutamine and subsequent glutaminolysis is critical for activation of the mTORC1 nutrient-sensing pathway, which regulates cell growth and protein translation in cancer cells. This is of particular interest in breast cancer, as glutamine dependence is increased in high-risk breast cancer subtypes. Pharmacological inhibitors of ASCT2-mediated transport significantly reduced glutamine uptake in human breast cancer cell lines, leading to the suppression of mTORC1 signalling, cell growth and cell cycle progression. Notably, these effects were subtype-dependent, with ASCT2 transport critical only for triple-negative (TN) basal-like breast cancer cell growth compared with minimal effects in luminal breast cancer cells. Both stable and inducible shRNA-mediated ASCT2 knockdown confirmed that inhibiting ASCT2 function was sufficient to prevent cellular proliferation and induce rapid cell death in TN basal-like breast cancer cells, but not in luminal cells. Using a bioluminescent orthotopic xenograft mouse model, ASCT2 expression was then shown to be necessary for both successful engraftment and growth of HCC1806 TN breast cancer cells in vivo. Lower tumoral expression of ASCT2 conferred a significant survival advantage in xenografted mice. These responses remained intact in primary breast cancers, where gene expression analysis showed high expression of ASCT2 and glutamine metabolism-related genes, including GLUL and GLS, in a cohort of 90 TN breast cancer patients, as well as correlations with the transcriptional regulators, MYC and ATF4. This study provides preclinical evidence for the feasibility of novel therapies exploiting ASCT2 transporter activity in breast cancer, particularly in the high-risk basal-like subgroup of TN breast cancer where there is not only high expression of ASCT2, but also a marked reliance on its activity for sustained cellular proliferation.

Development of a zona-free method of nuclear transfer in the mouse.

In the present study, a zona-free nuclear transfer (NT) technique, which had been originally developed in cattle, was modified for the mouse. Steps involved in this approach include removing the zona pellucida and enucleating without a holding pipette; sticking donor cells to the cytoplast before electric pulses are applied to fuse them and culturing reconstructed embryos individually in single droplets, to prevent aggregation. Control zona-free and zona-intact embryos from mated donors showed no significant difference in development to blastocyst, but did show reduced development to term. Removal of the zona pellucida affected the response to activation by strontium in the absence of calcium as a significant proportion of zona-free control oocytes and embryos reconstructed by NT lysed during this treatment. A comparison between cumulus and ES cells as donor cells revealed significant differences in fusion efficiency (58.1 +/- 4.0%, n = 573 vs. 42.9 +/- 2.2%, n = 2064, respectively, p < 0.001), cleavage (77.2 +/- 3.4%, n = 334 vs. 40.8 +/- 2.7%, n = 903, respectively, p < 0.001) but not for development to morula/blastocyst (8.7 +/- 2.1%, n = 334 vs. 13.9 +/- 1.8%, n = 903, respectively, p < 0.1). The stage at which embryo development arrested was also affected by donor cell type. A majority of embryos reconstructed from cumulus cells arrested at two-cell stage, usually with two nuclei, whereas those reconstructed from ES cells arrested at one-cell stage, usually with two pseudo-pronuclei. After transfer of ES cell-derived NT embryos, a viable cloned mouse was produced (3.0% of transferred embryos developed to term). These observations establish that a zona-free cloning approach is possible in the mouse, although further research is required to increase the efficiency.

Could sequential individual peer reviewed mortality audit data be used in appraisal?

BACKGROUND: Surgeons have traditionally monitored mortality as part of their surgical practice. The aim of this study was to determine whether peer review surgical mortality data might be useful in appraisal. METHODS: Since 1994, the Scottish Audit of Surgical Mortality (SASM) has performed critical event analysis of deaths under surgical care in Scotland. The anonymised, peer reviewed records of 16 consenting surgeons from a single Trust were reviewed over a three year period (2000-2002). RESULTS: Compliance with this voluntary audit was high at 97%. Individual surgeon profiles and comparison with colleagues in similar surgical practice demonstrated adverse events were infrequent and usually due to problems with the process of care rather than individual surgeon errors. The number of case note reviews requested increased significantly over the three years (chi square 9.5, p<0.01) although there was no significant change in the mean number of deaths per surgeon (18) or mean number of adverse events per surgeon (4). CONCLUSIONS: The use of sequential individual peer reviewed mortality data for anonymised comparison with local colleagues is now in use in appraisal and has potential for the revalidation process. This could provide reassurance that individual surgeons are complying with the General Medical Council concept of "good clinical practice" and highlight local problems in the process of care.

Nuclear transfer in practice.

The technique of nuclear transfer (NT) allows the production of embryos, fetuses, and offspring from a range of embryonic, fetal, and adult derived cell types in a range of species. Successful development is dependent upon numerous factors, including type of recipient cell, source of recipient cell, method of reconstruction, activation, embryo culture, donor cell type, and donor and recipient cell cycle stages. The present review will discuss the uses of NT, the techniques presently available, and the factors affecting subsequent development.

Bile acids, the "barrier," and reflux-related clinical disorders of the gastric mucosa.

The present communication represents an effort to provide an overview of the available evidence (and speculation) which suggests that an interrelationship exists between bile acids, the so-called "gastric mucosal barrier," and certain clinical diseases of the gastric mucosa in which reflux of upper intestinal content appears to be a pathophysiologic common denominator.

Acute gastric mucosal ulcerogenesis is dependent on the concentration of bile salt.

Studies on animals implicating reflux of bile salts in formation of "stress ulcer" often are suspect because of the inordinately high intragastric concentrations of bile salts used to induce experimental acute gastric mucosal damage. We studied reflux of bile salt in 11 patients after operation. Nine refluxed bile salts in a mean intragastric concentration of 1.87 +/- 0.24 mM. (range, 0.34 to 4.88 mM.). In the present study, therefore, the ulcerogenic potential of physiologic concentrations of bile salts was evaluated. With use of vascularized, chambered canine gastric mucosa, groups of animals were studied during three consecutive periods. Group A = topical acid test alone (ATS) during periods 1, 2, and 3; Group B = (1) ATS, (2) ATS, (3) ATS + vasopressin (VP = 0.1 U per Kg.-min. via the splenic artery); Group C = (1) ATS, (2) ATS + topical 1 mM. sodium taurocholate (TC), (3) ATS + 1 TC + VP; Group D = (1) ATS, (2) ATS + 2 TC, (3) ATS + 2 TC + VP; Group E = (1) ATS (2) ATS + 5 TC, (3) ATS + 5 TC + VP. Parameters evaluated were (1) net fluxes H+, Na+; (2) electrical potential difference (PD); (3) clearance of aminopyrine, a measure of mucosal blood flow (MBF); and (4) formation of lesions, graded zero to six by an independent observer who used photographs. In nonischemic mucosa, bile salts produced no ulcers, a significant concentration-dependent increase in H+ "back diffusion" and fall in PD, and a noncentration-dependent increase in MBF. In ischemic mucosa, the combination of topical acid, topical bile salts, and mucosal ischemia was acutely ulcerogenic. The severity of mucosal injury was dependent on the concentration of bile salt (y = 0.108 + 1.53x, r = 0.90, p less than 0.01). These data indicate that acute mucosal damage occurs in the presence of physiologic concentrations of bile salt, i.e., those routinely found in the gastric contents of postoperative patients.

Differing ulcerogenic potential of dihydroxy and trihydroxy bile acids in canine gastric mucosa.

Although recent clinical reports suggest that greater than normal amounts of dihydroxy secondary bile acids appear in the gastric content of patients with postoperative alkaline reflux gastritis, the pathophysiologic significance of these observations is unclear. We addressed this problem by usiong chambered ex vivo wedges of proximal canine gastric wall. The effects of 1 and 2 mM concentrations of the dihydroxy secondary bile acid, taurodeoxycholic, were compared with those of its parent trihydroxy primary bile acid, taurocholic. The parameters of mucosal function evaluated included the net flux of hydrogen ion, the transmural electrical potential difference, mucosal blood flow determined by radiolabeled microsphere embolization, and the severity of mucosal damage induced in mucosa rendered ischemic by wedge-specific intra-arterial low-dose vasopressin infusin. The results indicate that at each concentration in both ischemic and nonischemic mucosa the dihydroxy secondary bile acid induced a greater depression in potential difference, a more profound increase in mucosal permeability to hydrogen ion, and in ischemic mucosa a more severe degree of gross mucosal damage than did the trihydroxy primary bile acid. These effects may be related to a greater lipid solubility and consequent capacity to disrupt cell membranes.

Sensory neuron-mediated gastric mucosal protection is blocked by cyclooxygenase inhibition.

BACKGROUND: Sensory neurons have been proposed to play a critical role in the protection of the gastric mucosa from a variety of necrotizing agents. The purposes of this study were (1) to investigate the effect of topical capsaicin, a sensory neuron stimulant, on the gastric mucosal injury caused by the topical application of low concentrations of bile acid and (2) to determine whether local neuronal blockade with topical lidocaine or cyclooxygenase blockade with systemic indomethacin has any effect during pretreatment with capsaicin. METHODS: Before injury with topical 5 mmol/L acidified taurocholate (pH 1.2) rat stomachs were pretreated with either vehicle or capsaicin (160 mmol/L), both with and without prior administration of either lidocaine (1%) or indomethacin (5 mg/kg subcutaneously). Injury was assessed by measuring net transmucosal ion fluxes, the appearance of deoxyribonucleic acid into the gastric lumen, and gross and histologic injury scores. RESULTS: Pretreatment with topical capsaicin significantly (p < 0.05) decreased bile acid-induced net luminal ion fluxes and luminal deoxyribonucleic acid accumulation, an effect blocked by both lidocaine and indomethacin. CONCLUSIONS: Thus both local neuronal blockade and cyclooxygenase inhibition block the protective effect of capsaicin, findings corroborated by gross and histologic injury analysis. This study suggests that sensory neurons may mediate gastric mucosal protection from bile acid injury by increasing synthesis of endogenous prostaglandins.

Effect of topical bile acids on gastric surface epithelial cells.

UNLABELLED: Attempts to assess the integrity of the gastric surface epithelial cell layer have been hampered by the lack of a quantitative index of surface cell injury. Two approaches: scanning electron microscopy and measurement of DNA efflux (DNAE) were used to assess surface cell injury produced by topical bile acids. Taurocholic acid (TC) at 0, 2.5, 5, and 10 mM concentrations in both neutral (NTS, pH = 7.0) and acid test solution (ATS, pH = 1.2) was applied to chambered vascularized wedges of proximal canine gastric mucosa for sequential 30-minute study periods. In part I surface cell morphology was assessed by scanning electron microscopy in 28 mucosae exposed to NTS, NTS + TC, ATS, or ATS + TC, and the effect of the mucolytic agent N-acetyl-L-cysteine (acetylcysteine) at pH 7.0 was studied in 10 additional mucosae. In part II DNAE, net cation fluxes, and mean potential difference (PD) per 30-minute period were measured. In 16 animals 10% acetylcysteine was applied topically after period III to dissolve gastric mucus and allow recovery of exfoliated cells. Nineteen additional mucosae were treated with acetylcysteine between each study period. RESULTS: By scanning electron microscopy, mucosae exposed to NTS, NTS + TC, or ATS maintained an intact layer of surface epithelial cells. ATS + TC induced dose-dependent exfoliation of sheets of surface cells. Compared with NTS, neither NTS + TC nor ATS altered DNAE; DNAE increased only in mucosae exposed to ATS + TC. Compared with ATS, ATS + TC increased cation fluxes and decreased PD (p less than 0.05). DNAE correlated with delta H+, delta Na+, delta K+, and PD (r = 0.95, 0.93, 0.86, and 0.89) (all p less than 0.05). Pretreatment with acetylcysteine increased Na+ flux in mucosae exposed to NTS and ATS but otherwise did not change delta H+, delta K+, DNAE, or PD. In mucosae exposed to ATS + TC, DNAE paralleled morphologic changes in the surface epithelial layer and physiologic alterations in cation fluxes and PD. Both scanning electron microscopy and measurement of DNAE appear to be useful tools in assessing surface epithelial cell injury.

Adaptive cytoprotection of gastric surface epithelial cells against injury by physiologic concentrations of bile acid.

The purpose of this study was to determine whether adaptive cytoprotection of gastric mucosa could be demonstrated with concentrations of bile acid, which is normally found in the human stomach, and whether cyclooxygenase inhibition, in turn, could blunt the response. Surface epithelial cell exfoliation and ion fluxes were used as end points. A transduodenal gastric cannula was placed, and the pylorus/gastroesophageal junction was ligated in adult male Sprague-Dawley rats that had been anesthetized. In experiment 1 (N = 30), rat stomachs were exposed for 15 minutes to 5 ml of either a neutral test solution (160 mmol/L NaCl, pH 7) or 1 mmol/L acidified taurocholate (ATC) (100 mmol/L HCl, 60 mmol/L NaCl, 1 mmol/L taurocholic acid; pH 1.2). All rats were subsequently exposed for 15 minutes to 5 mmol/L ATC during which time mucosal injury was assessed by measuring net flux of H+, Na+, and K+, volume, and DNA efflux. In experiment 2 (N = 35), all stomachs were pretreated for 15 minutes with 1 mmol/L ATC before mucosal injury with 5 mmol/L ATC (15 minutes). Eighteen rats were pretreated with indomethacin (5 mg/kg) subcutaneously 75 minutes before the experiment was begun, and the same parameters were measured. Pretreatment of rat gastric mucosa with 1 mmol/L ATC significantly attenuated the mucosal injury that was seen with subsequent exposure to 5 mmol/L ATC, resulting in significantly (p less than 0.05) less luminal H+ loss (-16 +/- 4 vs -32 +/- 4 mEq/15 min) and DNA efflux (181 +/- 21 vs 270 +/- 25 micrograms/15 min) than the nonadapted group. Indomethacin pretreatment significantly attenuated the adaptive protective response, resulting in greater loss of H+ (-29 +/- 4 vs -18 +/- 3) and DNA efflux (190 +/- 35 vs 110 +/- 18, both p less than 0.05) after exposure to 5 mmol/L ATC. These studies demonstrate that adaptive cytoprotection of gastric mucosa occurs with physiologic concentrations of an irritant that is normally present in the stomach. Indomethacin blunts this effect, which suggests that adaptive cytoprotection in this setting may be mediated by production of endogenous prostaglandins.

Capsaicin-induced gastric mucosal hyperemia and protection: the role of calcitonin gene-related peptide.

BACKGROUND: Topical capsaicin augments gastric mucosal blood flow and is cytoprotective. This phenomenon is blocked by nitric oxide (NO) synthase and cyclooxygenase inhibition. Capsaicin-sensitive neurons store and release calcitonin gene-related peptide (CGRP). The purpose of this investigation was to study the effects of a CGRP antagonist on capsaicin-induced hyperemia and protection and to determine the role of NO and the cytoprotective prostaglandin PGE2 in this process. METHODS: The glandular stomachs in male Sprague-Dawley rats (280 to 350 gm) were chambered with the blood supply intact. Animals were divided into four groups. Normal saline solution (group 1) or the CGRP antagonists hCGRP8-37 (groups 2 through 4, 0.047 mg/ml) were continuously infused intraarterially via a retrograde splenic artery catheter at a rate of 0.034 ml/min after rats were given an intravenous bolus of either NSS (groups 1 and 2), L-arginine (group 3), or D-arginine (group 4) (200 mg/kg). The gastric mucosa was then topically exposed to normal saline solution (pH 7.4), followed by 160 mumol/L capsaicin and then 100 mmol/L acidified taurocholate (pH 1.2), each for 15 minutes. Gastric mucosal blood flow (ml/min/100 gm tissue) was continuously measured (laser Doppler) and mucosal injury was assessed. Luminal PGE2 production was measured during the bile acid injury period by radioimmunoassay. RESULTS: The CGRP antagonist hCGRP8-37 significantly inhibits capsaicin-induced hyperemia and its associated mucosal cytoprotection and also significantly decreases luminal mucosal PGE2 production. Pretreatment with L-arginine, but not D-arginine, reverses these effects of CGRP antagonism. CONCLUSIONS: CGRP is a mediator of capsaicin-induced hyperemia and protection. This effect may be dependent on both NO and PGE2 production.

Does bacteremia pose a direct threat to synthetic vascular grafts?

This study was undertaken to determine the significance of graft lumen exposure to blood-borne organisms in the development of graft infection. Three groups of dogs were studied. In group I (n = 20), the infrarenal aorta was dissected from surrounding tissue, divided, and reconstructed with a Dacron tube interposition graft. In group II (n = 9) the aorta was similarly isolated, but Dacron graft material was wrapped around the intact aorta. In group III (n = 13) the infrarenal aorta was isolated, but no graft material was placed. All dogs were given intravenous 1 X 10(7) Staphylococcus aureus at the completion of surgery. Group I grafts were harvested 8 hours, 1 day, or 21 days after bacterial challenge. Group II and III grafts were harvested 1 day or 21 days after infusion. At the time of harvest, selective cultures of the periaortic tissue (PAT), periaortic graft (PAG), and interposition graft lumen (GL) were taken. The overall infection rates were similar, with 17 of 20 (85%) dogs in group I, 6 of 9 (67%) in group II, and 11 of 13 (85%) in group III found to be culture positive. In group I, 3 of 3 dogs at 8 hours, 2 of 2 on day 1, and 12 of 15 on day 21 had positive PAT cultures. Only 4 of 15 on day 21 had positive GL cultures. In group II, 4 of 5 dogs on day 1 and 2 of 4 on day 21 had positive PAT and PAG cultures. In group III, 9 of 9 animals on day 1 and 2 of 4 on day 21 had positive PAT cultures. All aortic lumen cultures were negative in groups II and III. The difference between GL and PAT cultures was statistically significant in all groups (I, p = 0.01; II, p = 0.05; III, p = 0.01). Serial quantitative blood cultures revealed a mean bacterial load of 10.5 +/- 4.5 CFU/ml at 15 minutes postinfusion, which fell steadily until no bacteria were detected at 3.5 hours. Lymphangiography demonstrated periaortic pooling of lymph in the immediate postoperative period. These data suggest that the bacteremia in this model is transient and rapidly clears. Periaortic tissues quickly sequester bacteria, possibly because of lymphatic leakage. The GL appears to be secondarily infected.

Ultrasound in the evaluation of normal and induced ovulation.

In the past several years sonography has become an invaluable research tool for the investigation of spontaneous and induced ovulation and has added to the understanding of folliculogenesis and reproductive endocrinology. In practical terms, in ovulation induction sonography assists in the evaluation of the number and distribution of follicles, necessary for adequate interpretation of estrogen levels. Although there is no ideal size when it can be assumed that a follicle is mature, estimation of follicle size is of value and is a good guide to the timing of hCG administration. If the follicles are extremely small or there is evidence of hyperstimulation, these observations, together with the E2 levels, may be used to decide whether a further ultrasonic examination is warranted for the assessment of follicular growth or whether the treatment cycle should be abandoned. Provided follicular size is within normal limits, the diameter of the largest follicle may also be used in IVF programs to determine when the patient should be admitted to the hospital for more intensive monitoring of follicular development and the administration of hCG. Ultrasound is also valuable in patients with only one ovary accessible to laparoscopy. Even if the largest follicle is in the inaccessible ovary, the treatment cycle does not have to be abandoned, provided that several follicles are developing in the contralateral ovary. If neither ovary is accessible laparoscopically, percutaneous oocyte aspiration offers the patient the opportunity of IVF and embryo transfer.

How is the source of food poisoning outbreaks established? The example of three consecutive Salmonella enteritidis PT4 outbreaks linked to eggs.

Three consecutive outbreaks of Salmonella enteritidis PT4 occurred in Wales in 1989 in which epidemiological and microbiological investigation established eggs as the likely source although kitchen inspection and food preparation histories suggested other vehicles of infection. This paper examines the contribution of analytical epidemiology in attributing causation, with particular reference to those limitations which are regarded as inherent in epidemiological evidence. Such evidence, implicating eggs in the three outbreaks, fulfilled 6/7 widely accepted criteria for causation; data to assess the seventh were lacking. Collaboration between different agencies and professionals in investigating outbreaks is very important.

Experimental subarachnoid hemorrhage in the cynomolgus monkey: evaluation of treatment with hypertension, volume expansion, and ventilation.

We evaluated the treatment regime of dopamine-induced hypertension in association with volume expansion and ventilatory support in an experimental subarachnoid hemorrhage (SAH) model using the cynomolgus monkey. Regional cerebral blood flow, vessel caliber, intracranial pressure, and other pertinent physiological parameters were monitored throughout each study. We report the results for nine animals receiving treatment after an induced SAH and compare them with results obtained in a group of five animals not treated after SAH. Improvements in cerebral blood flow, vessel caliber, and morbidity and mortality rates were seen with this treatment. Seven of nine animals were alive at 20 hours after SAH in the treatment group, whereas all five animals in the untreated group died before this time. The mechanisms of action of this treatment are discussed. (Neurosurgery, 6: 57--62, 1980)

Mediators of bile acid-induced alterations in gastric mucosal blood flow.

The topical application of acidified (pH 1.2) bile acids to acid-peptic-secreting gastric mucosa increases mucosal blood flow, an important protective event because, when it is blunted, gross mucosal injury occurs. The mediators of this response are unknown. The current study examined the potential roles of luminal pH, luminal bile acid concentration, and, indirectly, endogenous prostaglandin generation in groups of dogs prepared with ex vivo chambered wedges of proximal gastric wall. Parameters evaluated included H+ fluxes, mucosal blood flow using radiolabeled microspheres, and the severity of gross mucosal injury induced at high and low intraluminal pH (7 and 1.2), at differing concentrations of bile acid (0, 2.5, 5.0 mM), in the presence of indomethacin pretreatment with or without concomitant close intra-arterial infusion of prostacyclin. The results indicate that topical bile acids increase mucosal blood flow in proportion to their capacity to induce H+ loss. This response is blunted (but not ablated) by indomethacin, resulting in gross mucosal injury, effects that are reversed by prostacyclin infusion. Thus, in large part, endogenous prostaglandins are its likely mediators.