The Impact of Smoking on Hospital Course and Postoperative Outcomes in Patients With Fracture-Related Infections

OBJECTIVES

To assess the relationship between patient smoking status and fracture-related infection (FRI) characteristics including patient symptoms at FRI presentation, bacterial species of FRI, and rates of fracture union.

METHODS

DESIGN

Retrospective cohort study.

SETTING

Urban level 1 trauma center.

PATIENT SELECTION CRITERIA

All patients undergoing reoperation for FRI from January 2013 to April 2021 were identified through manual review of an institutional database.

OUTCOME MEASURES AND COMPARISONS

Data including patient demographics, fracture characteristics, infection presentation, and hospital course were collected through review of the electronic medical record. Patients were grouped based on current smoker versus nonsmoker status. Hospital course and postoperative outcomes of these groups were then compared. Risk factors of methicillin-resistant Staphylococcus aureus (MRSA) infection, Staphylococcus epidermidis infection, and sinus tract development were evaluated using multivariable logistic regression.

RESULTS

A total of 301 patients, comprising 155 smokers (51%) and 146 nonsmokers (49%), undergoing FRI reoperation were included. Compared with nonsmokers, smokers were more likely male (69% vs. 56%, P = 0.024), were younger at the time of FRI reoperation (41.7 vs. 49.5 years, P < 0.001), and had lower mean body mass index (27.2 vs. 32.0, P < 0.001). Smokers also had lower prevalence of diabetes mellitus (13% vs. 25%, P = 0.008) and had higher Charlson Comorbidity Index 10-year estimated survival (93% vs. 81%, P < 0.001). Smokers had a lower proportion of S. epidermidis infections (11% vs. 20%, P = 0.037), higher risk of nonunion after index fracture surgery (74% vs. 61%, P = 0.018), and higher risk of sinus tracts at FRI presentation (38% vs. 23%, P = 0.004). On multivariable analysis, smoking was not found to be associated with increased odds of MRSA infection.

CONCLUSIONS

Among patients who develop a FRI, smokers seemed to have better baseline health regarding age, body mass index, diabetes mellitus, and Charlson Comorbidity Index 10-year estimated survival compared with nonsmokers. Smoking status was not significantly associated with odds of MRSA infection. However, smoking status was associated with increased risk of sinus tract development and nonunion and lower rates of S. epidermidis infection at the time of FRI reoperation.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Branched chain amino acids selectively promote cardiac growth at the end of the awake period

Essentially all biological processes fluctuate over the course of the day, manifesting as time-of-day-dependent variations with regards to the way in which organ systems respond to normal behaviors. For example, basic, translational, and epidemiologic studies indicate that temporal partitioning of metabolic processes governs the fate of dietary nutrients, in a manner in which concentrating caloric intake towards the end of the day is detrimental to both cardiometabolic and cardiovascular parameters. Despite appreciation that branched chain amino acids impact risk for obesity, diabetes mellitus, and heart failure, it is currently unknown whether the time-of-day at which dietary BCAAs are consumed influence cardiometabolic/cardiovascular outcomes. Here, we report that feeding mice a BCAA-enriched meal at the end of the active period (i.e., last 4 h of the dark phase) rapidly increases cardiac protein synthesis and mass, as well as cardiomyocyte size; consumption of the same meal at the beginning of the active period (i.e., first 4 h of the dark phase) is without effect. This was associated with a greater BCAA-induced activation of mTOR signaling in the heart at the end of the active period; pharmacological inhibition of mTOR (through rapamycin) blocked BCAA-induced augmentation of cardiac mass and cardiomyocyte size. Moreover, genetic disruption of the cardiomyocyte circadian clock abolished time-of-day-dependent fluctuations in BCAA-responsiveness. Finally, we report that repetitive consumption of BCAA-enriched meals at the end of the active period accelerated adverse cardiac remodeling and contractile dysfunction in mice subjected to transverse aortic constriction. Thus, our data demonstrate that the timing of BCAA consumption has significant implications for cardiac health and disease.

Increased cholesterol efflux in apolipoprotein AI (ApoAI)-producing macrophages as a mechanism for reduced atherosclerosis in ApoAI((-/-)) mice

The concentration of apolipoprotein (apo) AI in the artery wall is thought to enhance cellular cholesterol efflux and protect against atherosclerosis. It has been shown that although macrophages do not make apoAI, they respond to it by increased cholesterol efflux. We hypothesized that macrophage production of apoAI would increase cholesterol efflux and reduce atherogenesis. In this study, we produced mice expressing human apoAI under the control of the macrophage-specific scavenger receptor-A promoter (mphi-AI). Human apoAI was detectable in the serum HDL fraction of mphi-AI transgenic mice at concentrations too low to affect serum cholesterol or HDL levels. Immunoblotting showed the presence of human apoAI in transgenic macrophage culture supernatants, mostly as lipoprotein-free protein, with a small component associated with HDL-like particles. Atherosclerosis studies using apoAI((-/-)) mice transplanted with mphi-AI bone marrow showed that in the absence of macrophage-derived apoE, local expression of apoAI reduced diet-induced lesions in the proximal aorta. Additionally, mphi-AI macrophages showed a 40% increase in cholesterol efflux compared with control macrophages. These data support the hypothesis that apoAI production by macrophages in the artery wall is protective against atherosclerosis. This protection is likely mediated by increased cholesterol efflux and decreased foam cell formation in vivo.

Reduced atherosclerotic lesions in mice deficient for total or macrophage-specific expression of scavenger receptor-A

The absence of the scavenger receptor A (SR-A)-I/II has produced variable effects on atherosclerosis in different murine models. Therefore, we examined whether SR-AI/II deficiency affected atherogenesis in C57BL/6 mice, an inbred strain known to be susceptible to diet-induced atherosclerotic lesion formation, and whether the deletion of macrophage SR-AI/II expression would modulate lesion growth in C57BL/6 mice and LDL receptor (LDLR)(-/-) mice. SR-AI/II-deficient (SR-AI/II(-/-)) female and male mice on the C57BL/6 background were challenged with a butterfat diet for 30 weeks. No differences were detected in plasma lipids between SR-AI/II(-/-) and SR-AI/II(+/+) mice, whereas both female and male SR-AI/II(-/-) mice had a tremendous reduction (81% to 86%) in lesion area of the proximal aorta compared with SR-AI/II(+/+) mice. Next, to analyze the effect of macrophage-specific SR-AI/II deficiency in atherogenesis, female C57BL/6 mice were lethally irradiated, transplanted with SR-AI/II(-/-) or SR-AI/II(+/+) fetal liver cells, and challenged with the butterfat diet for 16 weeks. In a separate experiment, male LDLR(-/-) mice were reconstituted with SR-AI/II(-/-) or SR-AI/II(+/+) fetal liver cells and challenged with a Western diet for 10 weeks. No significant differences in plasma lipids and lipoprotein profiles were noted between the control and experimental groups in either experiment. SR-AI/II(-/-)-->C57BL/6 mice, however, had a 60% reduction in lesion area of the proximal aorta compared with SR-AI/II(+/+)-->C57BL/6 mice. A similar level of reduction (60%) in lesion area was noted in the proximal aorta and the entire aorta en face of SR-AI/II(-/-)-->LDLR(-/-) mice compared with SR-AI/II(+/+)-->LDLR(-/-) mice. These results demonstrate in vivo that SR-AI/II expression has no impact on plasma lipid levels and that macrophage SR-AI/II contributes significantly to atherosclerotic lesion formation.

Urea reduction ratio and urea kinetic modeling: a mathematical analysis of changing dialysis parameters

Based mainly on the simplicity of its calculation, the urea reduction ratio (URR) has been suggested as an alternative to urea kinetic modeling (Kt/V) as a measure of hemodialysis adequacy. However, recent studies have raised questions concerning the accuracy of URR, particularly in the presence of residual kidney function (KrU). This study was initiated to evaluate the relationship between URR and Kt/V under a variety of dialysis conditions. Equations based on the variable-volume, single-pool model described by Gotch were used to construct a model incorporating the variables used in the estimation of URR and Kt/V. The model's prediction of URR correlated closely with measured URR in 30 patients (r = 0.9987, p < 0.000001). This analytic approach showed that changes in each of several dialysis parameters caused divergence in the values of URR and Kt/V. The model showed that URR could be less than 0.65, while total Kt/V was greater than 1.2, whether or not KrU was present. In fact, when KrU was greater than 1. 0, URR could be less than 0.65, while Kt/V might be 2.0 or higher. On the other hand, the model showed instances where URR could be greater than 0.65, when Kt/V was less than 1.2. This occurred only when KrU was less than 1.0. To determine the prevalence of these anomalies in clinical practice, 767 kinetic modeling determinations were evaluated in 207 patients. One of the above discrepancies was observed at least once in 30.9% of the patients, representing 12.1% of all determinations. In addition, it was found that omitting KrU from the calculation of Kt/V generally leads to a Kt/V <1.2. This, when associated with a URR <0.65, could erroneously imply inadequate dialysis. The patient data are consistent with the view that URR and Kt/V are the net result of several variables that may act together or even in opposing directions. Based on this mathematical model and the observed clinical data, the use of URR alone to assess dialysis adequacy, or neglecting the contribution of KrU to Kt/V, may lead to changes in the dialysis prescription that are neither correct nor necessary.

Macrophage lipoprotein lipase promotes foam cell formation and atherosclerosis in vivo

Expression of lipoprotein lipase (LPL) by the macrophage has been proposed to promote foam cell formation and atherosclerosis, primarily on the basis of in vitro studies. LPL-deficient mice might provide a model for testing the role of LPL secretion by the macrophage in an in vivo system. Unfortunately, homozygous deficiency of LPL in the mouse is lethal shortly after birth. Because the fetal liver is the major site of hematopoiesis in the developing fetus, transplantation of C57BL/6 mice with LPL-/- fetal liver cells (FLCs) was used to investigate the physiologic role of macrophage LPL expression in vivo. Thirty-four female C57BL/6 mice were lethally irradiated and reconstituted with FLCs from day 14 LPL+/+, LPL+/-, and LPL-/- donors. No significant differences were detected in plasma levels of post-heparin LPL activity or in serum cholesterol or triglyceride levels between the 3 groups on either a chow diet or an atherogenic diet. After 19 weeks on the atherogenic diet, aortae were collected for quantitative analysis of the extent of aortic atherosclerosis. LPL expression was detected by immunocytochemistry and in situ hybridization in macrophages of aortic atherosclerotic lesions of LPL+/+-->C57BL/6 and LPL+/--->C57BL/6 mice, but not in LPL-/--->C57BL/6 mice, whereas myocardial cells expressed LPL in all groups. The mean aortic lesion area was reduced by 55% in LPL-/--->C57BL/6 mice compared with LPL+/+-->C57BL/6 mice and by 45% compared with LPL+/--->C57BL/6 mice, respectively. These data demonstrate in vivo that LPL expression by macrophages in the artery wall promotes foam cell formation and atherosclerosis. off

Analysis of three decision-making methods: a breast cancer patient as a model

PURPOSE

To compare three decision making techniques using a common clinical problem.

METHODS

Two recently developed methods, the analytic hierarchy process (AHP) and the analytic network process (ANP), were compared with a Markov process in the evaluation of the optimal post-lumpectomy treatment strategy for an elderly woman with a mammographically detected, nonpalpable early-stage breast cancer. The following treatment alternatives were considered: observation, radiation, tamoxifen, combination radiation and tamoxifen, and simple mastectomy. All three decision methods incorporated patient preferences.

RESULTS

The models agreed on the ranking of the preferred treatment, radiation and tamoxifen, but there were variations in the rankings of the other treatment choices. Individual differences between the three models were uncovered. The Markov process provided estimates of quality-adjusted life expectancy and distribution of health events. Both AHP and ANP required less development time than the Markov process.

CONCLUSION

All three methods may be useful tools to the clinician in analyzing complex medical problems. The Markov is the most labor-intensive method but provides detailed results, whereas the AHP and the ANP give only rank orders of the alternatives. The most important considerations in choosing between these methods are time to project completion and the detail of information sought.

Treatment of early-stage breast cancer in the elderly: a health-outcome-based approach

PURPOSE

To evaluate the post-lumpectomy treatment of a nonpalpable, stage I, T1b tumor, mammographically detected, in a 74-year-old woman without comorbidities.

METHODS

A Markov process, through 120 monthly cycles, was used to model patient progression through a treatment program, employing literature data and a health-outcome utility. Treatments considered were: observation; radiation totaling 5,000 cGy over six weeks; tamoxifen, 20 mg/day, for five years; simple mastectomy; and radiation therapy plus tamoxifen. Health states included absence of disease (NED), loco-regional recurrence, distant metastasis, age-sex-race (ASR)-adjusted death, cancer mortality, treatment complications, and post-mastectomy death. Transition probabilities were established from the literature. Health-state utilities were determined from the responses of health care professionals to a basic reference gamble.

RESULTS

Quality-adjusted life years (QALYs) were determined to be 8.19 for radiation plus tamoxifen, decreasing to 8.04 for mastectomy, a difference of only a 0.15 years (1.8 months). Sensitivity analysis, however, showed relative stability in the ranking among treatment options.

CONCLUSION

Although the model showed little difference between QALYs with the treatments, the combination of radiation and tamoxifen provides the optimal therapy for this case.

Increased atherosclerosis in mice reconstituted with apolipoprotein E null macrophages

Macrophage-derived foam cells express apolipoprotein E (apoE) abundantly in atherosclerotic lesions. To examine the physiologic role of apoE secretion by the macrophage in atherogenesis, bone marrow transplantation was used to reconstitute C57BL/6 mice with macrophages that were either null or wild type for the apoE gene. After 13 weeks on an atherogenic diet, C57BL/6 mice reconstituted with apoE null marrow developed 10-fold more atherosclerosis than controls in the absence of significant differences in serum cholesterol levels or lipoprotein profiles. ApoE expression was absent in the macrophage-derived foam cells of C57BL/6 mice reconstituted with apoE null marrow. Thus, lack of apoE expression by the macrophage promotes foam cell formation. These data support a protective role for apoE expression by the macrophage in early atherogenesis.

Leukocyte low density lipoprotein receptor (LDL-R) does not contribute to LDL clearance in vivo: bone marrow transplantation studies in the mouse

The targeted disruption of the low density lipoprotein (LDL) receptor gene in mice results in accumulation of plasma LDL cholesterol and in predisposition to diet-induced aortic atherosclerosis. Although the liver is the central organ for receptor mediated clearance of LDL, the in vivo role of other organs and tissues in LDL catabolism has not been directly studied. Since bone marrow-derived cells such as blood leukocytes and tissue macrophages express LDL receptors and contribute a large mass to the body, we designed bone marrow transplantation (BMT) experiments to reconstitute LDL receptor null mice [LDL-R(-/-)] with marrow obtained from LDL-R wild-type mice [LDL-R(+/+)] and evaluate the effects on parameters of plasma lipid metabolism. Although reconstitution of the transplanted mice with donor bone marrow cells was complete, no differences in plasma lipid levels and lipoprotein distribution were found between groups, irrespective of the diet used, and turnover studies using 125I-labeled LDL showed that LDL receptor expression by leukocytes and macrophages does not significantly contribute to plasma LDL clearance. The complementary experiment of transplanting LDL-R(-/-) marrow into C57BL/6 recipients [LDL-R(-/-)-->LDL(+/+)], performed to evaluate the role of leukocyte LDL-R in normocholesterolemic condition, also produced no effects on plasma lipid parameters. LDL binding studies using macrophages isolated from transplanted mice showed a lack of LDL-R expression. Thus, despite their large number and wide distribution, bone marrow-derived cells do not significantly influence receptor-mediated clearance of plasma LDL.

Sequential test selection in the analysis of abdominal pain

Numerous decision-making tools exist to assist physicians in diagnosis management. However, the accuracy of available clinical information is often ambiguous or unknown and current analytical models do not explicitly incorporate judgementally defined information. A model encompassing both physician judgment and probability analysis was developed to accommodate such data. A problem requiring sequential diagnostic testing was structured utilizing the analytic hierarchy process (AHP). The case presented involved a patient complaining of upper abdominal pain who, after initial evaluation, did not need immediate surgery. Physicians were faced with identifying the optimal sequence of diagnostic testing. The criteria used for test selection included minimizing risk, patient discomfort, and cost of testing and maximizing diagnostic capability. Although at the onset the "best" test choice was unknown, the clinical picture indicated four test alternatives: upper gastrointestinal series (GI), abdominal ultrasonography (US), abdominal computed tomography (CT), and upper gastrointestinal endoscopy (END). Based upon the relative preferences of the criteria utilized, the AHP analysis indicated that upper GI series was the optimal first test. Given a negative test, posterior probabilities were calculated using Bayes' theorem, resulting in a new estimate of diagnostic capability. The AHP analysis was reiterated, identifying abdominal ultrasonography as the optimal second test. This analysis may be repeated as many times as necessary. Sensitivity analysis demonstrated that changing criteria preferences may alter the choice of tests and/or their sequence.

Quality assurance in anatomic pathology: automated SNOMED coding

This case study details the set-up and implementation of the PathNet autocoder (Cerner Corporation) in a busy anatomic pathology laboratory. After initial start-up, procedures were developed to improve the system's performance. Four classes of software coding errors were identified, and an index was developed to measure the number of cases between errors (CBE). Through modifications in the program, the CBE increased sharply by the end of the six-month study period. During the last three months of the study, the efficiency of case retrieval was tested by comparing manual and electronic methods on the same reference cases. This demonstrated significant time saving and removed the variability of manual coding. The technique employed in this study may assist other institutions seeking to implement such a coding system within their respective environments.

Optimal interval for triple-lumen catheter changes: a decision analysis

A survey of 53 university and community hospitals revealed that 73% of the institutions had no standard policy for the replacement of triple-lumen catheters (TLCs). Since the maintenance of a TLC in place for a prolonged period may lead to infectious complications, it appeared warranted that standards of management be developed. A decision-tree model was constructed for evaluating the optimal time for changing a TLC that would minimize infection. Cost estimates and health effects at three-, five-, and ten-day change intervals were considered for catheter insertion and complications resulting from such insertion. The results suggested that prophylactic catheter changes should occur no later than every five days, provided that there are no signs of infection. However, sensitivity analysis of several variables suggested that individual institutions should establish policy timing changes based upon careful interpretation of their own data. A model was developed to assist in determining the optimal time to change a TLC based upon such data.

Cell survival in rabbit gastric glands: effect of extracellular pH, osmolarity, and anoxia

Although backdiffusion of luminal acid is regarded as a common mechanism of gastric injury, the extracellular pH (pHo) at which cells are irreversibly injured is not well defined. Exclusion of the fluorescent dye propidium iodide was used to estimate cell survival in rabbit gastric glands incubated in buffers of pHo 8.0-2.0. Mean survival (+/- SE) for n = 6 experiments at 2 h in a HEPES buffer of 300 mosM at pHo 8.0, 7.0, 6.0, 4.0, and 2.0 was 80 +/- 3, 91 +/- 2, 90 +/- 2, 71 +/- 2, and 17 +/- 4%, respectively. Survival at acidic pHo was improved in a high KCl buffer: 78 +/- 3 and 38 +/- 7% at pHo 4.0 and 2.0, respectively. Survival in HCO3- buffers was 73 +/- 3, 88 +/- 2, and 92 +/- 3% at pHo 8.0, 7.4, and 6.0. Brief (5 min) exposure to pHo 4.0 followed by reexposure to pHo 7.4 had no effect on acid secretion as estimated by [14C]aminopyrine uptake or cellular viability over 4 h. The influence on cell survival of changes in pHo under conditions of chemical anoxia and in buffers of different osmolarity was investigated. Chemical anoxia was induced using 2.5 mM KCN and 2.0 mM iodoacetic acid (IAA) to inhibit oxidative phosphorylation and anaerobic glycolysis. Survival in glands exposed to KCN and IAA in HEPES buffer was 54 +/- 5, 82 +/- 3, and 87 +/- 2% at pHo 8.0, 7.0, and 6.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hypoxia on function and morphology of in vitro frog gastric mucosa

The effects of gaseous hypoxia and reoxygenation on oxynticopeptic (OPC) and surface mucous cells (SMC) were examined in in vitro bullfrog gastric fundic mucosae mounted in Ussing chambers. Forskolin-stimulated H+ secretion, transmucosal potential difference (PD), and electrical resistance (R) were monitored in tissues incubated in HCO3(-)-free or HCO3(-)-containing buffer. At serosal pH (pHs) 7.2, 1 h of hypoxia with 100% N2 resulted in a decrease in PD, increase in R, and complete inhibition of H+ secretion. After 30 min of hypoxia, the morphology of OPC changed from the secretory to the nonsecretory state without recognizable cytopathology. Destructive changes in OPC increased progressively at pHs 7.2 as the hypoxic period was prolonged from 4 to 24 h. After 4 h of reoxygenation following 12-24 h of hypoxia, OPC remained necrotic and H+ secretion showed no recovery, whereas in some areas where SMC were exfoliated adjacent SMC showed epithelial restitution. The recovery of H+ secretion and PD during 2 h of reoxygenation after 4 h of hypoxia at pHs 6.0 and 6.8 was less than that at 7.2 and 8.0 and was greater in the presence of serosal HCO3- than its absence at pHs 7.2. These results suggest that, in in vitro frog gastric mucosa, 1) OPC are more vulnerable to hypoxia than SMC, 2) basolateral acidosis exaggerates hypoxic injury of OPC, and 3) serosal HCO3- protects OPC from hypoxic injury.

Prostaglandin stimulates Cl(-)-HCO3- exchange in amphibian oxynticopeptic cells

Prostaglandins, shown to stimulate Cl- transport in epithelial cells of several different tissues, protect gastric mucosa against physiological injury induced by luminal acid. To clarify the relationship between the stimulation of Cl(-)-transport and the protection of gastric mucosa, the effect of prostaglandin on Cl(-)-HCO3- exchange in oxynticopeptic cells (OPC) was examined in intact sheets of in vitro frog gastric mucosa, in which OPC were selectively loaded with the pH-sensitive fluorescent dye 2',7'-bis(carboxyethyl)-5(6')-carboxyfluorescein (BCECF). In omeprazole (0.3 mM)-pretreated frog fundic mucosae, in which H+ secretion was totally inhibited, 16,16-dimethyl prostaglandin E2 (dmPGE2) induced a significant decrease in intracellular pH (pHi) in OPC simultaneously with a significant increase in pHi in adjacent muscularis mucosae, an effect abolished by removal of ambient Cl- or addition of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) (0.5 mM). dmPGE2 accentuated the rates of alkalinization of OPC after either removal of ambient Cl- or addition of serosal H2DIDS. During exposure to luminal or serosal acid, dmPGE2 significantly attenuated acidification of OPC induced by the exogenous H+, effects abolished either by removal of ambient Cl- or by addition of H2DIDS (0.5 mM). These results suggest that 1) dmPGE2 stimulates extrusion of HCO3- through the basolateral Cl(-)-HCO3- exchanger in resting OPC (H+ secretion inhibited) and that 2) relatively high extracellular [HCO3-] on the basolateral surface afforded by dmPGE2 protects OPC from acidification during exposure to luminal or serosal acid.

H(+)-K(+)-ATPase contributes to regulation of pHi in frog oxynticopeptic cells

The effect of intracellular acidosis on luminal H+ secretion and the role of H(+)-K(+)-ATPase in regulation of intracellular pH (pHi) in oxynticopeptic cells (OPC) (measured with a pH-sensitive fluorescent dye) were examined in intact sheets of in vitro frog (Rana catesbeiana) gastric mucosa. Intracellular acidosis of OPC induced by decreasing pH in the serosal solution (pHs) from 7.2 to 6.0 reversibly increased forskolin-stimulated H+ secretion without increasing endogenous histamine release. The observed increase in H+ secretion was unaffected by either 1 mM cimetidine or 1 mM histamine, but was accentuated by 1 mM amiloride, an effect abolished by 0.3 mM omeprazole. Steady-state pHi values in stimulated or resting OPC at pHs 7.2 were not significantly different. However, pHi in OPC was significantly higher in stimulated than in resting tissues at pHs 6.9, a difference accentuated by decreasing pHs to 6.4 or by 1 mM amiloride. Amiloride completely prevented recovery from intracellular acidosis induced by pHs 6.4 or 6.9 in omeprazole-treated tissues, but only partially mitigated recovery in cimetidine- or forskolin-treated tissues. At pHs 6.4, high luminal [K+] (100 mM) increased H+ secretion and hastened recovery of pHi in cimetidine-treated tissues in the presence of amiloride. These results suggest that, in intact sheets of in vitro frog gastric mucosa, 1) intracellular acidosis stimulates luminal H+ secretion via histamine-independent mechanisms and 2) H(+)-K(+)-ATPase contributes to the recovery of OPC from intracellular acidosis.

Effect of luminal acid on intracellular pH in oxynticopeptic cells in intact frog gastric mucosa

The effect of changes in luminal [H+] on intracellular pH in oxynticopeptic cells was examined using intact sheets of frog (Rana catesbeiana) gastric mucosa in which oxynticopeptic cells were selectively loaded with the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). The serosal solution was buffered with either HCO3- or N-2-hydroxymethylpiperazine-N'-2-ethanesulfonic acid (HEPES). Luminal pH was decreased from 7.2 to 1.5 and changed back to 7.2. In stimulated (forskolin-treated) tissues, intracellular pH decreased at luminal pH 1.5 only in HEPES, with complete recovery at 7.2. In resting (omeprazole-treated) tissues, intracellular pH began to decrease at luminal pH 2.0 in HEPES and at 1.5 in HCO3-, with complete recovery at 7.2 in both. In resting tissues bathed in Cl(-)-free HEPES, the recovery of intracellular pH at luminal pH 7.2 was completely prevented by serosal amiloride (1 mmol/L) but was not affected by serosal 4,4'-diisothiocyanatodihydrostilbene-2-2'-disulfonic acid (H2-DIDS; 0.5 mmol/L). In resting tissues bathed in Cl(-)-free HCO3-, the recovery of intracellular pH at luminal pH 7.2 was not affected by amiloride but was prevented partially by H2-DIDS and completely by combination of H2-DIDS and amiloride or by removal of ambient Na+. These results suggest that during exposure to high luminal [H+]: (a) stimulated oxynticopeptic cells maintain a steady intracellular pH more readily than resting cells; (b) serosal HCO3- protects oxynticopeptic cells from intracellular acidosis; and (c) both Na+/H+ exchange and Na(+)-HCO3- cotransport are involved in the recovery from intracellular acidosis in resting oxynticopeptic cells.

Influence of Cl- on pH(i) in oxynticopeptic cells of in vitro frog gastric mucosa

The effect of Cl- on intracellular pH (pH(i)) was studied using sheets of frog (Rana catesbeiana) fundic mucosa in which oxynticopeptic cells were selectively loaded with the acetomethoxy ester form of the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF/AM). Before the measurement of pH(i), tissues were exposed to either 10(-5) M forskolin in the serosal solution (stimulated tissues) or 3 x 10(-4) omeprazole in the serosal solution (inhibited tissues). In HCO3- and N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffers, pH(i) increased significantly after removal of Cl- from serosal and luminal solution, both in stimulated and inhibited tissues. The presence of Cl- in the luminal solution prevented this rise in pHi, an effect abolished by serosal 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS, 3 x 10(-4) M) but not by serosal amiloride (10(-3)M). In the presence of serosal Cl-, pH(i) increased after exposure to serosal DIDS, more prominently in the stimulated than in the inhibited tissues. These results confirm the presence of a Cl(-)-HCO3-exchanger in the basolateral membrane of oxynticopeptic cells in intact sheets of mucosa and suggest that luminal Cl- contributes to the regulation of pH(i) in oxynticopeptic cells.

Effect of PCO2 on intracellular pH in in vitro frog gastric mucosa

Steady-state intracellular pH (pHi) in 0, 5, and 10% CO2-buffered Ringer solution in sheets of in vitro frog gastric antral or fundic mucosa has been measured using the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). In tissues perfused with N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)-100% O2 buffer [extracellular pH (pHo) = 7.14], steady-state pHi in antral surface cells was 7.08 +/- 0.06 (n = 8), in fundic oxynticopeptic cells 6.91 +/- 0.03 (n = 13), in the muscularis mucosa 7.58 +/- 0.06 (n = 4). In mucosae perfused with 17.8 mM HCO3- -95% O2-5% CO2 buffer (pHo = 7.14), steady-state pHi in antral surface cells was 6.97 +/- 0.02 (n = 22), in fundic oxynticopeptic cells 7.00 +/- 0.04 (n = 18), and in fundic muscularis mucosa 7.39 +/- 0.05 (n = 8). In fundic oxynticopeptic cells perfused with 35.6 mM HCO3- -90% O2-10% CO2 (pHo = 7.14) steady-state pHi was 6.77 +/- 0.07 (n = 4). In tissues equilibrated initially with 100% O2 and changed to 5% CO2, antral surface cells acidified by 0.21 pH units and fundic oxynticopeptic cells by 0.10 pH units, with restoration of pHi to resting levels within 30 and 10 min, respectively. Exposure of tissues initially equilibrated with 5% CO2 to 100% O2 alkalinized antral surface cells by 0.22 pH units and fundic oxynticopeptic cells by 0.23 pH units, with only partial recovery of pHi by 30 min. These data suggest that steady-state pHi is equivalent in surface and oxynticopeptic cells and is lower than in the muscularis mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)

Secretagogue-induced changes in intracellular pH and amylase release in mouse pancreatic acini

The response of the intracellular pH (pHi) to stimulation of enzyme secretion in pancreatic acini was measured using the fluorescent dye 2'-7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. Acini suspended in pH 7.40 buffer demonstrated cytoplasmic alkalinization of 0.17, 0.14, and 0.15 pH units 2 min after addition of the secretagogues carbachol (10(-5) M), caerulein (10(-10) M), and bromo-A23187 (10(-6) M). Corresponding net stimulated amylase secretion over 30 min was 9.2, 10.3, and 5.6% of total content, respectively. Pretreatment of acini with atropine blocked the pHi rise induced by carbachol; addition of atropine 2 min after the carbachol did not reverse the alkalinization. Acini suspended in Ca2+ free buffer containing 0.1 or 0.2 mM ethylene glycol tetraacetic acid showed 0.21 and 0.10 pH unit alkalinization in response to caerulein (10(-10) M) and carbachol (10(-5) M) but no change in pHi after addition of bromo-A23187. Amylase release in response to increasing concentrations of caerulein was maximal at 10(-10) M, with decreasing rates of amylase release at higher drug concentrations (10(-8), 10(-7) M). Alkalinization in response to stimulation of secretion was maximal at 10(-8) M caerulein (0.30 pH units at 2 min) but was of lesser magnitude at 10(-7) M. Pancreatic acini demonstrated autoregulation of pHi over a range of external pH from 7.4 to 7.1. Net amylase release over 30 min in response to 10(-5) M carbachol was sustained at normal levels in buffers of pH varying between 7.7 and 6.5. In contrast, cytoplasmic alkalinization in response to carbachol occurred only in buffers with pH values between 7.40 and 7.10. These results indicate that amylase release occurs over a wide range of pHi and is not invariably associated with secretagogue-induced alkalinization.

Structure of the sidechain of lipopolysaccharide from Pseudomonas syringae pv. morsprunorum C28

The sidechain of the lipopolysaccharide from the phytopathogen Pseudomonas syringae pv. morsprunorum C28 was shown to be composed of D-rhamnose. Using 1H and 13C-NMR spectroscopy, methylation analysis, Smith degradation and optical rotation data, the repeat unit was found to have the structure: ----3)-D-Rhap-(alpha 1----3)-D-Rhap-(alpha 1----2)-D-Rhap-(alpha 1---- and a degree of polymerization of approximately 70. Attention is drawn to the possible prevalence of D-6-deoxyhexoses in the lipopolysaccharides of plant pathogenic bacteria.

Effect of topical bile acids on gastric surface epithelial cells

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.

Early gastric cancer

Although common in Japan, early gastric cancer (EGC = gastric adenocarcinoma confined to the mucosa and submucosa of the stomach, with or without regional lymph node metastases) is thought to be an infrequent occurrence in the United States. However, a review of all "curative" resections for carcinoma of the gastric body and antrum at the University of Virginia between 1974 and 1982 revealed EGC in five of 31 patients (16%). The purpose of the present study was to compare EGC to more advanced gastric cancer (ADV; n = 26) to determine whether any presenting historical, laboratory, x-ray, or endoscopic features distinguished the two groups before surgery and to ascertain whether postoperative survival in the United States mimicked the Japanese experience. All surviving patients were contacted, all charts were abstracted, all pathologic specimens were reexamined, and all radiographs were reviewed blindly by an experienced radiologist. Statistical evaluation was accomplished using Kaplan-Meier plots, chi square analysis, and unpaired "t" tests, as appropriate. At presentation, patients with EGC were younger (44 +/- 6 vs. 67 +/- 2 years, p less than 0.01) with higher admission albumin levels (4.1 +/- 0.2 vs. 3.7 +/- 0.1 mgm/dl, p less than 0.01). Although not significantly different, admission hemoglobin tended to be higher (41 +/- 2 vs. 35 +/- 2%), the incidence of weight loss tended to be less (40 vs. 65%), duration of symptoms tended to be longer (21 +/- 11 vs. 8 +/- 3 months), and tumor diameter tended to be smaller (1.7 +/- 0.6 vs. 5.8 +/- 0.7 cm) in EGC. No differences were apparent with respect to endoscopic or radiographic appearance, tumor location (greater than 70% antrum), presence of regional lymph node metastases (EGC = 2/5; ADV = 20/26), or type of resection (subtotal gastrectomy in 4/5 EGC, in 19/26 ADV). On median 5-year follow-up, however, survival with EGC has been 100%. In contrast, the Kaplan-Meier estimate of 5-year survival in ADV is 15% (42% with muscularis invasion, 0% with serosal invasion, 12% with extra-gastric spread; p less than 0.01 vs. EGC). One suture line recurrence in EGC was successfully treated by re-resection. No ADV patient with recurrence survives (p less than 0.01). Thus, EGC behaves similarly in the United States and Japan; for example, prognosis is excellent even in the presence of lymph node metastases. Inability to distinguish EGC from ADV before surgery justifies an aggressive surgical approach to all patients with resectable gastric neoplasms.

The cellular basis of metastatic bone disease in patients with lung cancer

Histologic patterns of tumor-bone interaction were systematically evaluated in 80 cases of metastatic lung cancer involving bone. Patterns of tumor-bone interaction varied with the histologic type of lung cancer, reflecting the biochemical and biologic differences among the different types of lung cancer. Evidence presented here suggests that destruction of bone by metastatic lung cancer is mediated neither by direct contact of tumor cells with bone matrix nor by release of diffusible substances that lyse bone matrix. Among indirect mechanisms, the most prevalent and important was the activation of bone-lining cells by metastatic tumor. Epidermoid carcinomas in particular were associated with histologic patterns of classical bone remodelling, including osteoblastic, osteoclastic, and osteocytic activity. Adenocarcinomas showed a particularly high association with microfractures and manifested a stromal pattern consistent with release of prostaglandins. Ischemic necrosis of bone due to compression of vessels by expanding tumor mass is also a common and important mechanism. Correlation of histologic patterns with reported data on the frequency of metastases and syndromes of ectopic hormone production provides insight into the mechanism(s) of paraneoplastic hypercalcemia in patients with lung cancer.

Lowering of plasma cholesterol levels in free-living adolescent males; use of natural and synthetic polyunsaturated foods to provide balanced fat diets

Two hundred and twenty-nine adolescent male pupils, attending two boarding schools, participated in a study, under free-living dietary conditions, designed to assess the effects on plasma lipids of altering only the type and not the amount of dietary fat. The students were monitored for 6 weeks on three different diets. During the first study period, dietary changes comprised substituting a polyunsaturated dried "filled" milk and products derived therefrom for conventional dairy products (diet A). The second dietary phase involved replacing all meat and dairy products with equivalent polyunsaturated ruminant fat products (diet B). The third period consisted of a control diet of conventional dairy and meat products. During both polyunsaturated diets a 14% reduction in plasma cholesterol was achieved compared with control levels. Low-density lipoprotein cholesterol was similarly suppressed. A greater decrease in plasma cholesterol of 19-21% was recorded in those pupils with initial cholesterol levels greater than 230 mg/dl. There was no significant difference in plasma triglycerides between diet A and the control diet whereas the triglyceride levels were 16.5% lower during diet B. The fall in plasma cholesterol coincided with an increase in plasma triglyceride linoleate from 8% to 19% of total triglyceride fatty acids. Dietary analysis of the pupils' diet indicated an increase in the ratio of polyunsaturates to saturates from 0.27 during the control period to 1.08 on the dried filled milk and 0.90 on the polyunsaturated ruminant fat products. A palatability survey showed that both the dried filled milk and the polyunsaturated ruminant fat products were as well accepted by the pupils as the conventional products. The results suggest that such products could, if introduced to the general population, play an important part in plasma cholesterol suppression in the hope that this would significantly reduce the incidence of coronary artery disease.