Serial Procalcitonin as a Predictor of Bacteremia and Need for Intensive Care Unit Care in Adults With Pneumonia, Including Those With Highest Severity: A Prospective Cohort Study

Background

Procalcitonin (PCT) is a prohormone that rises in bacterial pneumonia and has promise in reducing antibiotic use. Despite these attributes, there are inconclusive data on its use for clinical prognostication. We hypothesize that serial PCT measurements can predict mortality, intensive care unit (ICU) admission, and bacteremia.

Methods

A prospective cohort study of inpatients diagnosed with pneumonia was performed at a large tertiary care center in Boston, Massachusetts. Procalcitonin was measured on days 1 through 4. The primary endpoint was a composite adverse outcome defined as all-cause mortality, ICU admission, and bacteremia. Regression models were calculated with area under the receiver operating characteristic curve (AUC) as a measure of discrimination.

Results

Of 505 patients, 317 patients had a final diagnosis of community-acquired pneumonia (CAP) or healthcare-associated pneumonia (HCAP). Procalcitonin was significantly higher for CAP and HCAP patients meeting the composite primary endpoint, bacteremia, and ICU admission, but not mortality. Incorporation of serial PCT levels into a statistical model including the Pneumonia Severity Index (PSI) improved the prognostic performance of the PSI with respect to the primary composite endpoint (AUC from 0.61 to 0.66), bacteremia (AUC from 0.67 to 0.85), and need for ICU-level care (AUC from 0.58 to 0.64). For patients in the highest risk class PSI >130, PCT was capable of further risk stratification for prediction of adverse outcomes.

Conclusion

Serial PCT measurement in patients with pneumonia shows promise for predicting adverse clinical outcomes, including in those at highest mortality risk.

Modeling Immune Response to BK Virus Infection and Donor Kidney in Renal Transplant Recipients

In this paper we develop and validate with bootstrapping techniques a mechanistic mathematical model of immune response to both BK virus infection and a donor kidney based on known and hypothesized mechanisms in the literature. The model presented does not capture all the details of the immune response but possesses key features that describe a very complex immunological process. We then estimate model parameters using a least squares approach with a typical set of available clinical data. Sensitivity analysis combined with asymptotic theory is used to determine the number of parameters that can be reliably estimated given the limited number of observations.

Regulation of JNK signaling by GSTp

Studies of low basal Jun N-terminal kinase (JNK) activity in non-stressed cells led us to identify a JNK inhibitor that was purified and identified as glutathione S-transferase Pi (GSTp) and was characterized as a JNK-associated protein. UV irradiation or H2O2 treatment caused GSTp oligomerization and dissociation of the GSTp-JNK complex, indicating that it is the monomeric form of GSTp that elicits JNK inhibition. Addition of purified GSTp to the Jun-JNK complex caused a dose-dependent inhibition of JNK activity. Conversely, immunodepleting GSTp from protein extracts attenuated JNK inhibition. Furthermore, JNK activity was increased in the presence of specific GSTp inhibitors and a GSTp-derived peptide. Forced expression of GSTp decreased MKK4 and JNK phosphorylation which coincided with decreased JNK activity, increased c-Jun ubiquitination and decreased c-Jun-mediated transcription. Co-transfection of MEKK1 and GSTp restored MKK4 phosphorylation but did not affect GSTp inhibition of JNK activity, suggesting that the effect of GSTp on JNK is independent of the MEKK1-MKK4 module. Mouse embryo fibroblasts from GSTp-null mice exhibited a high basal level of JNK activity that could be reduced by forced expression of GSTp cDNA. In demonstrating the relationships between GSTp expression and its association with JNK, our findings provide new insight into the regulation of stress kinases.

Assessment of regional left ventricular wall stress after myocardial infarction by echocardiography-based structural analysis

OBJECTIVES

The objective of this study was to determine the distribution of regional left ventricular (LV) wall stress after myocardial infarction (MI).

BACKGROUND

After a large MI, structural changes occur in the heart that ultimately may lead to alterations in LV size and shape, a process generally referred to as ventricular remodeling. Regional variation in myocardial wall stress may be responsible for initiation of physiologic and cellular changes that result in myocardial hypertrophy, dilatation, and remodeling after MI. Simplified geometric analytic methods of estimating global LV wall stress cannot determine regional variation such as that occurring after MI.

METHODS AND RESULTS

To assess regional LV wall stress after MI, we applied the finite element method to patient-specific end-systolic LV models generated from echocardiographic imaging. After validation by comparison with analytic solutions of LV wall stress in idealized ventricles, LV models were constructed from rotated orthogonal apical images from 13 normal volunteers, 16 patients with recent (<4 days) anterior MI, and 7 patients with recent infero-posterior MI. The mean Von Mises stress was calculated for the entire LV and for 5 separate regions of the LV. Von Mises LV wall stress was increased globally in patients with anterior MI (211 +/- 46 kdyne/cm2; P < .002) or infero-posterior MI (175 +/- 23 kdyne/cm2; P = .04) compared with normal patients (144 +/- 57 kdyne/cm2). Global wall stress correlated directly with ejection fraction (P < .0001) and inversely with wall motion index (P < .004) in patients with anterior MI. Wall stress in the apical regions was increased by a factor of 2.3 in patients with anterior MI (P < .0001), whereas other regions did not differ from normal patients. There were no individual regions that were significantly different from normal in patients with infero-posterior MI.

CONCLUSIONS

Anterior MI is associated with an increase in apical end-systolic wall stress compared with normal and infero-posterior MI. This may be an important stimulus for LV remodeling after anterior MI.

Portal hypertension predisposes the gastric mucosa to hemorrhagic shock/reperfusion injury

We have previously demonstrated that the portal hypertensive (PHT) gastric mucosa has unique functional and morphologic features which predispose it to increased damage by noxious agents such as aspirin or alcohol. In this study we examine the PHT gastric mucosa following hemorrhagic shock and reperfusion. Portal hypertension was produced in 12 rats using staged portal vein occlusion, and seven animals (controls) underwent sham procedures. All rats received 2 ml 0.1 N HCl intragastrically. Shock was then induced by withdrawing blood to reduce systemic arterial pressures to approximately 30 mm Hg for 20 min. Blood was then reinfused and stomachs were excised 20 min later for gross and microscopic quantitation of injury. We found that gross damage to gastric glandular mucosa was more than doubled in PHT rats over sham-operated controls. In PHT gastric mucosa, deep histologic necrosis involved 22.5 +/- 3.8% of mucosal section lengths compared with 6.9 +/- 2.0% in control mucosa (P less than 0.005). Histologically, mucosal injury patterns were predominantly ischemic, with deep necrosis and disintegration of glands and microvessels, all prominently more extensive in PHT mucosa. We conclude that PHT gastric mucosa has significantly increased susceptibility to damage following hemorrhagic shock/reperfusion compared with portal normotensive mucosa. Since hemorrhagic shock is a frequent complication of portal hypertension, this study suggests clinical investigations of gastric mucosal function and pathophysiology in PHT patients following hemorrhage and resuscitation.

Effects of dietary fatty acid saturation on serum and tissue cholesterol concentrations and fecal sterol excretion: a chronic metabolic study in the rat

We studied the effect of the degree of fatty acid saturation on cholesterol metabolism in rats fed either a low cholesterol-low fat diet (control group), high cholesterol-low fat diet (Chol group), high cholesterol-high saturated fat diet (Chol-SF) or high cholesterol-high PUF diet (Chol-PUF). The highest serum cholesterol levels were found in the Chol-SF group. No significant difference in serum cholesterol was found between the Chol and Chol-PUF groups. The Chol-PUF group showed the greatest accumulation of cholesterol in the liver. There was no significant difference in fecal excretion of acidic sterols, cholesterol and coprostanol between the Chol-PUF and Chol-SF groups. We conclude that in chronic feeding experiments in rats: a) high dietary cholesterol intake results in hypercholesterolemia; b) the hypercholesterolemia is accentuated by high dietary SF but is unaffected by PUF; c) addition of PUF to high cholesterol diet leads to massive cholesterol accumulation in the liver which can partly account for the apparent hypocholesterolemic effect of PUF relative to SF; and d) differences in serum and tissue cholesterol levels between SF and PUF supplemented groups are unlikely to be due to their effects on fecal sterol excretion.

Effect of dimethylthiourea on plasma paraquat concentration

In a previous study, administration of the hydroxyl radical scavenger, dimethylthiourea (DMTU), and paraquat was associated with higher mortality in rats than was paraquat alone. In the present study, the possibility was evaluated that administration of DMTU increased plasma paraquat levels. Plasma paraquat concentrations were measured in Sprague-Dawley rats 1, 2, 4, 8 and 24 h after intraperitoneal (i.p.) injection of 29 mg paraquat cation/kg body wt. Another group of rats was treated identically except that they received i.p. injections of DMTU before injections of paraquat. Administration of DMTU was associated with increased plasma paraquat concentration (P less than 0.01). Pharmacokinetic analyses indicated that, compared to rats receiving paraquat alone, rats given paraquat and DMTU showed: (1) greater area under the paraquat concentration time-curve; (2) lower total body paraquat clearance; and (3) smaller apparent volume of distribution. Plasma biochemical studies indicated that paraquat caused hyperglycemia as well as an early reduction (compared to controls) in hepatic enzymes. We conclude that: (1) DMTU administration is associated with increased plasma paraquat concentrations; and (2) impaired synthesis or inhibition of release of hepatic proteins may be an early effect of paraquat.

Adverse effects of (15S)-15-methyl-prostaglandin E1 in normal and paraquat-exposed rats

Single, daily injections of approximately 1 mg/kg of (15S)-15-methyl-PGE1 (mPGE1), a PGE1 analog, have been reported to inhibit inflammation and to prolong survival in several animal models of local and systemic inflammation. We examined the effect of this dose of mPGE1 on paraquat toxicity in rats. A significant increase in early mortality was identified in mPGE1-treated rats as early as 3 hr following injection of paraquat and appeared associated with increased respiratory effort. Rats given mPGE1 without paraquat also appeared to increase respiratory effort but did not die. Rats killed at 3 hr following injections demonstrated increased lung weights in both paraquat-injected and control animals receiving mPGE1. Although a neutrophilia was identified in these animals, no significant increase in lung lavage neutrophils or albumin was identified. These data suggest that large intermittent doses of a PGE1 analog may adversely affect the respiratory system of normal and injured animals, and will accelerate mortality following exposure to potentially lethal doses of paraquat.

Properties of the Ca-activated K+ channel in pancreatic beta-cells

The existence of [Ca2+]i-activated K+-channels in the pancreatic beta-cell membrane is based in two observations: quinine inhibits K+-permeability and, increasing intracellular Ca2+ stimulates it. The changes in K+-permeability of the beta-cell have been monitored electrically by combining measurements of the dependence of the membrane potential on external K+ concentration and input resistance. The changes in the passive 42K and 86Rb efflux from the whole islet have been measured directly. Intracellular Ca2+ has been increased by various means, including increasing extracellular Ca2+, addition of the Ca2+-ionophore A23187 or noradrenaline and application of mitochondrial uncouplers and blockers. In addition to quinine, many other substances have been found to inhibit or modulate the [Ca2+]i-activated K+-channel. The most important of these is the natural stimulus for insulin secretion, glucose. Glucose may inhibit K+-permeability by lowering intracellular Ca2+. Glibenclamide, a hypoglycaemic sulphonylurea, is about 25 times more active than quinine in blocking the K+-channel in beta-cells. The methylxanthines, c-AMP, various calmodulin inhibitors and Ba2+ also inhibit K+-permeability. Genetically diabetic mice have been studied and show an alteration in the [Ca2+]i-activated K+-channel. It is concluded that the [Ca2+]i-activated K+-channel plays a major role in the normal function of the pancreatic beta-cell. The study of its properties should prove valuable for the understanding and treatment of diabetes.

[Kahler's disease manifesting mandibular localization]

The authors present a case of multiple myeloma, the diagnosis of which was made at the time of the appearance of a mandibular tumour following the extraction of a tooth.