Requirement for macrophage elastase for cigarette smoke-induced emphysema in mice.

To determine which proteinases are responsible for the lung destruction characteristic of pulmonary emphysema, macrophage elastase-deficient (MME-/-) mice were subjected to cigarette smoke. In contrast to wild-type mice, MME-/- mice did not have increased numbers of macrophages in their lungs and did not develop emphysema in response to long-term exposure to cigarette smoke. Smoke-exposed MME-/- mice that received monthly intratracheal instillations of monocyte chemoattractant protein-1 showed accumulation of alveolar macrophages but did not develop air space enlargement. Thus, macrophage elastase is probably sufficient for the development of emphysema that results from chronic inhalation of cigarette smoke.

Macrophage elastase (matrix metalloproteinase-12) suppresses growth of lung metastases.

Matrix metalloproteinases (MMP) have been implicated in virtually all aspects of tumor progression. However, the recent failure of clinical trials employing synthetic MMP inhibitors in cancer chemotherapy has led us to hypothesize that some MMPs may actually serve the host in its defense against tumor progression. Here we show that mice deficient in macrophage elastase (MMP-12) develop significantly more gross Lewis lung carcinoma pulmonary metastases than their wild-type counterparts both in spontaneous and experimental metastasis models. The numbers of micrometastases between the two groups are equivalent; thus, it seems that MMP-12 affects lung tumor growth, and not metastasis formation, per se. MMP-12 is solely macrophage derived in this model, being expressed by tumor-associated macrophages and not by tumor or stromal cells. The presence of MMP-12 is associated with decreased tumor-associated microvessel density in vivo and generates an angiostatic>angiogenic tumor microenvironment that retards lung tumor growth independent of the production of angiostatin. These data define a role for MMP-12 in suppressing the growth of lung metastases and suggest that inhibitors designed to specifically target tumor-promoting MMPs may yet prove effective as cancer therapeutics.

Accelerated lung amino acid release in hyperdynamic septic surgical patients.

Amino acid flux across the lungs was studied in humans to gain further insight into the altered nitrogen metabolism that characterizes catabolic disease states. Lung flux of glutamine, glutamate, and alanine was determined in three groups of surgical patients with indwelling pulmonary artery catheters: (1) preoperative controls (n = 14), (2) postoperative elective general surgical patients (n = 10, and (3) hyperdynamic septic surgical patients (n = 17). In controls the lung was an organ of amino acid balance. These exchange rates did not change in general surgical patients. In the septic group, glutamine release by the lung increased markedly from a control value of 0.80 +/- 0.99 mumol/kg per minute to 6.80 +/- 1.32 mumol/kg per minute. This accelerated release rate was secondary to both an increase in total pulmonary blood flow and an increase in the pulmonary artery-systemic arterial concentration difference. The lung also became an organ of significant alanine release in septic patients. The lung plays an active metabolic role in the processing of amino acids and may be a key regulator in interorgan nitrogen flux after major injury and infection.

Oral glutamine accelerates healing of the small intestine and improves outcome after whole abdominal radiation.

The healing effects of glutamine given orally for 8 days as a single amino acid nutrient after treatment with whole abdominal radiation (10 Gy) were studied. Rats received isonitrogenous and isovolumic diets containing 3% glutamine or 3% glycine. Control rats were not irradiated but were given identical diets. In irradiated animals, survival was 100% in animals receiving glutamine compared with 45% in animals receiving glycine. Glutamine ingestion diminished bloody diarrhea and the incidence of bowel perforation. Arterial glutamine level was higher in animals receiving glutamine in the diet, as were gut glutamine extraction (35% +/- 8% vs 12% +/- 7%) and intestinal glutaminase activity. These metabolic improvements were associated with a marked increase in villous height, villous number, and the number of mitoses per crypt in rats receiving glutamine. Glutamine was not beneficial in control nonirradiated animals. The data demonstrated that provision of oral glutamine after abdominal radiation supported gut glutamine metabolism, improved mucosal morphometrics, and decreased the morbidity and mortality associated with this abdominal radiation model.

Effects of ovariectomy and estradiol benzoate on high affinity choline uptake, ACh synthesis, and release from rat cerebral cortical synaptosomes.

Several presynaptic processes were studied in cerebral cortical synaptosomes prepared from intact adult female rats or from ovariectomized animals that received 3 subcutaneous injections of either estradiol benzoate (10 micrograms/kg) or vehicle. Injections were given 1/day, every other day, and animals were sacrificed 1 h after the last injection. High affinity choline uptake and coupled acetylcholine (ACh) synthesis were reduced by ovariectomy, and restored to control levels by the estradiol benzoate injections. In contrast, low affinity choline uptake and depolarization-induced [3H]ACh release were unaffected by either ovariectomy or estradiol benzoate injections. These results suggest that changes in estradiol levels may alter the high affinity transport process regulating ACh synthesis in this tissue.

Evaluation of the in-hospital Utstein template in cardiopulmonary resuscitation in secondary hospitals.

INTRODUCTION: The in-hospital Utstein template for cardiopulmonary resuscitation (CPR) was assessed in four secondary hospitals (334-441 beds) which did not have systematic data collection. MATERIALS AND METHODS: The reports and outcome over a period of 12 months during the years 2000-2001 were evaluated. RESULTS: Of a total of 1690 patients that had a cardiac arrest (CA), 204 (12%) were resuscitated. Information on the collected Utstein parameters were available as follows: initial rhythm in 91%, time interval from collapse to defibrillation (in case of ventricular fibrillation or ventricular tachycardia as initial rhythm) in 90%, time interval to return of spontaneous circulation (ROSC) in 83% and duration of resuscitation in 83%. ROSC was achieved in 69 patients (34%, CI 27-41%) and 34 (17%, CI 11-23%) survived to hospital discharge. Twenty patients showed satisfactory neurological recovery (10%, CI 6-14%). Eighteen (9%, CI 5-13%) patients were alive at 12 months from the event. Factors associated with survival to hospital discharge were VF/VT (P=0.007) as the initial rhythm and shorter interval to defibrillation (P=0.046). CONCLUSION: The in-hospital Utstein template was logical but laborious and it provided tools for resuscitation management evaluation in the study hospitals. For continuous use, a slightly compressed model may be warranted. In the present material, the overall survival rate to hospital discharge was in line with previous reports but there were somewhat less neurologically satisfactory survivors. There is an evident need to improve the outcome of patients suffering CA on the wards. An important step is to reduce the time interval to defibrillation.

Intestinal glutamine metabolism after massive small bowel resection.

Gut glutamine utilization after massive small bowel resection was studied to gain further insight into the alterations and adaptations in intestinal glutamine metabolism that occur during the development of post-resectional hyperplasia. After resection of the middle 60% of the small intestine in the rat, gut glutamine metabolism was studied immediately and 1, 2, and 3 weeks later. Whole gut glutamine extraction was 22% in sham controls and it acutely declined to 12% (p less than 0.01) after bowel resection. Extraction increased to 31% 1 week later (p less than 0.05) and then returned to normal by week 2. Gut ammonia release decreased after massive small bowel resection, whereas intestinal alanine release increased. The increase in gut glutamine extraction at 1 week occurred at a time when jejunal and ileal DNA and protein content were markedly increased (p less than 0.01). Intestinal glutaminase content declined initially and then increased by the third week after bowel resection (p less than 0.01). With time, increases in gut cellularity and glutaminase content are associated with gut glutamine utilization in the shortened small bowel that is equal to that of the intact unresected intestine.

Characterization of L-glutamine transport by type II alveolar cells.

This study characterized the sodium-dependent transport of L-glutamine (L-Gln) by rat type II alveolar cells. Uptake of 50 microM glutamine (Gln) was determined and found to be linear for at least 15 min. The sodium-dependent velocity represented greater than 80% of the total uptake at all time points. Kinetic studies of sodium-dependent Gln uptake at concentrations between 0.005 and 8 mM showed uptake to occur via two saturable transport systems, a high-affinity carrier [Michaelis constant (Km) = 259 +/- 19 microM, maximum velocity (Vmax) = 0.942 +/- 0.08 nmol.mg protein-1.30 s-1] and a low-affinity transporter (Km = 4.96 +/- 1.2 mM, Vmax = 2.98 +/- 0.19 nmol.mg protein-1.30 s-1). Uptake of Gln via the low-affinity system was nearly completely blocked by 10 mM 2-methylaminoisobutyric acid (MeAIB), and increasing concentrations of Gln almost totally inhibited transport of MeAIB, indicating the presence of system A. Further inhibition studies of the high-affinity transporter showed marked inhibition by serine, cysteine, and nonradioactive Gln. Lithium did not substitute for sodium, strongly suggesting that L-Gln was not transported by system N. Furthermore, transport of Gln by the high-affinity carrier was not affected by hormones or by changes in external pH. We conclude that sodium-dependent L-Gln transport by rat type II alveolar cells occurs predominantly via system A and system ASC.

Lung glutamine flux following open heart surgery.

Despite the attenuated skeletal muscle proteolysis that occurs following hypothermic anesthesia and open heart surgery, blood amino acid levels are maintained, suggesting enhanced amino acid release by another organ. To investigate the role of the lung in this response, we determined the release of glutamine (Gln) and alanine by the lung, since these two amino acids transport two-thirds of circulating amino acid nitrogen. Three groups of patients were studied: (a) preoperative non-stressed controls; (b) postoperative general surgical patients; and (c) postoperative cardiac surgical patients studied on Postoperative Day 1 following open heart surgery requiring cardiopulmonary bypass and hypothermic anesthesia. In preoperative controls the lung was an organ of glutamine and alanine balance. These exchange rates were unaffected by the stress of an abdominal surgical procedure despite a mild increase in pulmonary blood flow. However, lung Gln release in the cardiac surgical patients was significantly increased (-0.6 +/- 1.2 mumole/kg/min in controls vs -6.5 +/- 1.3 mumole/kg/min in postoperative hearts, P less than 0.05) and was due exclusively to an increase in the pulmonary artery-systemic arterial concentration difference. Alanine release by the lungs was also increased in the postoperative cardiac surgical patients. The mechanism by which this augmented pulmonary glutamine release occurs following open heart surgery is unclear, but the lungs appear to play a central role in maintaining amino acid homeostasis. This metabolic role of the lungs following hypothermic anesthesia and cardiopulmonary bypass has not been previously described.

Oral glutamine reduces bacterial translocation following abdominal radiation.

The effect of dietary glutamine on bacterial translocation was studied in rats following administration of a single dose of abdominal radiation (1000 rad) that causes a reproducible mucosal injury and results in a high incidence of culture-positive mesenteric lymph nodes after radiation (XRT). Following XRT, rats received only the amino acid glutamine (3%, +GLN) in their drinking water or a control nonessential amino acid (glycine, -GLN). Diets were isonitrogenous and isovolumetric. Four days after XRT, rats were anesthetized and a laparotomy was performed. Mesenteric lymph nodes were sterilely excised and cultured. Arterial blood was also obtained for whole blood glutamine determination. Control rats received no XRT but received identical diets. In XRT rats who received the GLN-free diet, the incidence of culture-positive mesenteric lymph nodes was 89% (eight of nine rats) while in the radiated rats receiving the GLN-enriched diet, the incidence fell to 20% (P less than 0.05). In non-radiated control rats receiving GLN-enriched and GLN-depleted diets for 4 days, bacterial translocation occurred in zero of eight and one of eight rats, respectively (NS). Provision of glutamine to XRT rats resulted in higher blood levels of glutamine (408 +/- 25 microM in XRT +GLN vs 311 +/- 19 microM in XRT -GLN, P less than 0.05). In addition, provision of GLN maintained mucosal mass and reduced weight loss (P less than 0.05). The data lend further support to the hypothesis that glutamine helps maintain the gut mucosal barrier and thereby decreases the incidence of bacterial translocation following bowel injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Prophylactic glutamine protects the intestinal mucosa from radiation injury.

Glutamine may be an essential dietary component, especially for the support of intestinal mucosal growth and function. This study evaluated the effects of a glutamine-enriched elemental diet, administered before whole-abdominal radiation on gut glutamine metabolism, mucosal morphometrics, and bacterial translocation. Rats were randomized to receive a nutritionally complete elemental diet that was glutamine-enriched or glutamine-free for 4 days. The animals were then subjected to a single dose of 1000 cGy x-radiation to the abdomen. After irradiation, all animals received the glutamine-free diet. Four days later the animals underwent laparotomy for sampling of arterial and portal venous blood, culture of mesenteric lymph nodes, and removal of the small intestine for microscopic examination. There was no difference in arterial glutamine or gut glutamine extraction between the two groups, but body weight loss was significantly diminished in the glutamine-fed rats. Rats receiving the glutamine-enriched elemental diet before radiation had a significant increase in jejunal villous number, villous height, and number of metaphase mitoses per crypt. Scanning electron microscopy confirmed the presence of an intact gut epithelium in eight of eight rats receiving prophylactic glutamine compared to one of eight animals in the glutamine-free group. Three of eight rats fed glutamine had culture positive mesenteric lymph nodes compared with five of seven rats receiving the glutamine-free diet. Glutamine exerts a protective effect on the small bowel mucosa by supporting crypt cell proliferation effect on accelerate healing of the acutely radiated bowel.