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S Shedlofsky

Publications and source records attributed to S Shedlofsky.

10 recordsLinked to original sources
PubMed1998

Stability of cephalosporin prodrug esters in human intestinal juice: implications for oral bioavailability.

The levels of degradation of cefetamet pivoxil (CAT), cefuroxime axetil (CAE), and cefpodoxime proxetil (CPD) in 0.6 M phosphate buffer (pH 7.4) and human intestinal juice (pH 7.4) at 37 degreesC over 24 h were compared. Significant differences in the time courses of degradation and in the patterns of degradation products were observed. (i) The relative proportions of the Delta2- and Delta3-cephalosporins were roughly reversed in the two incubation media. In phosphate buffer, the major degradation product was the Delta2-cephalosporin (CAT = 61%; CAE = 74%; CPD = 85%), while in intestinal juice it was the Delta3-cephalosporin (CAT = 86%; CAE = 75%; CPD = 87%). (ii) Generally, the degradation of the prodrug esters progressed faster in intestinal juice than in phosphate buffer (e.g., for CAT the half-lives [t1/2s] were 0.78 and 4.3 h, respectively). (iii) The two diastereoisomers of CAE and CPD were degraded at different rates in intestinal juice (for the CAE diasteroisomers, t1/2s = 0.37 and 0.93 h; for the CPD diastereoisomers, t1/2s = 0.18 and 0.98 h) but were degraded at similar rates in phosphate buffer (for the CAE diastereoisomers, t1/2 = 1.6 h; for the CPD t1/2 diastereoisomers, = 2.2 h). It is concluded that (i) the Delta2 isomerization does not significantly affect the bioavailability of prodrug esters since enzymatic hydrolysis in the intestinal fluid proceeds mainly to the active Delta3-cephalosporin and (ii) the high degree of stereoselectivity of the enzymatic ester hydrolysis should make it possible to increase the bioavailabilities of certain prodrug esters (CAE, CPD) by using the more stable diasterioisomer.

Administration, Oral↗
PubMed1997

Cytokines and alcoholic liver disease.

Chemical messengers called cytokines play an important role during the body's initial response to infection (i.e., acute inflammation). Cytokines attract and activate components of the immune system, promote blood clotting, and facilitate the release of additional chemical messengers. In addition, cytokines induce the liver to shift its physiological function, emphasizing inflammatory and immune responses at the expense of normal metabolism. Alcohol consumption may cause excessive cytokine production in the liver, leading to inflammatory liver disease. Researchers are seeking ways to moderate the toxic effects of cytokines while sparing their protective functions.

Animals↗
PubMed1992

Tumor necrosis factor in alcohol enhanced endotoxin liver injury.

Endotoxin administration causes liver injury. Patients with alcoholic liver disease frequently have portal vein and systemic endotoxemia, and some investigators have suggested that endotoxin plays an etiologic role in alcoholic liver injury. Many of the metabolic effects of endotoxin are mediated by the cytokine tumor necrosis factor (TNF). It was the purpose of this study to determine whether TNF plays a role in ethanol-enhanced endotoxin liver injury. Rats were fed either a diet in which 36% of the calories were from ethanol or an isocaloric control diet. After 6 weeks, groups of 10 rats were intravenously injected with either saline, 1 mg/kg endotoxin, or 30 micrograms/kg of a prostaglandin E1 (PGE1) analogue + 1 mg/kg endotoxin 24 hr prior to sacrifice. Ethanol/endotoxin-treated rats had significantly higher liver enzyme levels (ALT: 1064 +/- 355 IU/liter, AST: 2024 +/- 515 IU/liter) compared with isocaloric/endotoxin controls (ALT: 237 +/- 54 IU/liter, AST: 602 +/- 80 IU/liter). Ethanol/endotoxin rats also had significantly higher peak serum TNF concentrations (992 +/- 200 units/ml) compared with isocaloric/endotoxin controls (344 +/- 96 units/ml). Pretreatment of ethanol/endotoxin rats with PGE1 caused significant attenuation of liver injury (ALT: 267 +/- 64 IU/liter, AST: 612 +/- 77 IU/liter) and a diminished serum TNF response. In contrast to chronic ethanol administration, acute gavage with 2 mg/kg ethanol (30% w/v) followed by intravenous injection of 2 mg/kg endotoxin produced significantly lower peak serum TNF concentrations (401 +/- 76 units/ml) than gavage with distilled water (1152 +/- 208 units/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMed1992

Increased plasma interleukin-6 concentrations in alcoholic hepatitis.

Interleukin-6 (hepatocyte stimulating factor) is a 26 kd cytokine that plays a major role in the acute phase response, especially the hepatic aspects of the acute phase response. Patients with alcoholic hepatitis manifest many aspects of the acute phase response. In this 6-month study we evaluated serial plasma interleukin-6 levels in 30 consecutive patients with moderate to severe alcoholic hepatitis. Mean admission plasma interleukin-6 activity was markedly increased (49.8 +/- 8.5 U/ml, normal less than 5 U/ml) in patients with alcoholic hepatitis, and levels decreased with clinical improvement to 15.6 +/- 6.1 U/ml at 6 months. Admission interleukin-6 activity correlated significantly (r = 0.82) with the severity of liver disease as assessed by the discriminant function of Maddrey. Also measured were selected assays postulated to be regulated by interleukin-6, including serum albumin (2.3 +/- 0.1 gm/dl), which was significantly depressed; alpha 1-acid glycoprotein (52 +/- 5 mg/dl), which was within normal limits; and IgA (827 +/- 70 mg/dl) and C-reactive protein (3.03 +/- 0.51 mg/dl), which were significantly elevated. Interleukin-6 activity fell over time in a pattern similar to that of bilirubin and C-reactive protein. We suggest that plasma interleukin-6 may not only regulate many aspects of the acute phase response but also may be a marker of inflammation and severity of disease in alcoholic hepatitis.

Hepatitis, Alcoholic↗
PubMed1991

Lead enhances lipopolysaccharide and tumor necrosis factor liver injury.

Lead markedly augments the lethality of endotoxin lipopolysaccharide (LPS) in rats. In this model of LPS toxicity, the liver is severely injured. Much of the tissue injury produced by LPS is thought to be mediated by the cytokine tumor necrosis factor (TNF). Tumor necrosis factor recently has been speculated to be a mediator of several models of liver injury such as that produced by galactosamine. To investigate the possible role of TNF in the lead-enhanced LPS toxicity model, we administered doses of lead acetate (15 mg/kg), LPS (100 micrograms/kg), or TNF (6.25 x 10(6) U/kg) that produced minimal changes in liver enzymes. However, when lead was administered simultaneously with either LPS or TNF, serum aspartate transaminase, alanine transaminase, alkaline phosphatase, glutamyl transpeptidase, and plasma triglyceride levels were markedly increased. Lead + LPS treatment increased both peak serum TNF concentrations and TNF "area under the curve" as compared with LPS alone. We conclude that lead not only enhances LPS lethality but also LPS liver injury. Furthermore, lead enhances TNF liver injury and increases LPS-stimulated serum TNF levels. These data suggest that the lead-enhanced LPS model offers a system for studying TNF-induced liver injury.

Alanine Transaminase↗
PubMed1988

Clinical features of acetaminophen toxicity.

Thirteen patients met our criteria for severe acetaminophen hepatotoxicity over a 5-year study period. Six patients had therapeutic misadventures (not attempting suicide), and seven were attempting suicide. Five of six patients in the therapeutic misadventure group were chronic alcoholics, and three were taking other drugs reported to cause hepatic microsomal enzyme induction. In the suicide group, two of seven patients were alcoholics, and one patient was taking another inducing drug. All six patients in the therapeutic misadventure group had nausea, vomiting, or starvation, whereas two of seven patients in the suicide group had similar characteristics. Starvation could deplete the protective factor glutathione, thus augmenting hepatotoxicity. In the therapeutic misadventure group, four of six patients developed acute tubular necrosis, as compared to two of seven in the suicide group. One patient died in each group. Clinicians should be aware of these features as part of the spectrum of acetaminophen toxicity.

Acetaminophen↗
PubMed1981

Human intestinal mononuclear cells. II. Demonstration of a naturally occurring subclass of T cells which respond in the allogeneic mixed leukocyte reaction but do not effect cell-mediated lympholysis.

We have examined the T-cell functional capabilities of human intestinal mononuclear cells isolated from surgically obtained normal and inflammatory bowel disease intestinal specimens. Intestinal mononuclear cells have T cells present which respond to the mitogenic lectins E-PHA, Con A, and PWM and to foreign cell-surface antigens in the allogeneic-mixed leukocyte reaction. Intestinal mononuclear cells from ulcerative colitis patients exhibit a significantly decreased responsiveness in comparison to normal intestinal mononuclear cells with regard to both mitogenesis and the allogeneic-mixed leukocyte reaction; however, these defects may be secondary to the severity of the disease process that led to intestinal resection or the therapy which patients had received. Although both normal and inflammatory bowel disease intestinal mononuclear cells exhibit responsiveness in the allogeneic-mixed leukocyte reaction, thus indicating recognition of and sensitization by foreign cell-surface determinants, intestinal mononuclear cells do not subsequently kill the sensitizing cells in cell-mediated lympholysis. Therefore, the subclass of T cells which mediates cell-mediated lympholysis may either be absent from intestinal mononuclear cells or nonfunctional, while the subclass of T cells which responds in the allogeneic-mixed leukocyte reaction is both present and functional. This observation adds to the evidence of major functional differences between intestinal and peripheral blood mononuclear cells. Therefore, it will be necessary to better understand the factors regulating the effector capabilities of intestinal mononuclear cells before delineation of immunopathologic events in these tissues.

Adult↗
PubMed1980

Noncirrhotic nodular transformation of the liver with portal hypertension: clinical, angiographic, and pathological correlation.

Noncirrhotic nodular lesions of the liver are difficult to classify since the etiologies ofmost are unknown. Presented here is the case of a 21-yr-old man with portal hypertension and bleeding esophageal varices in which the gross and microscopic pathological findings have the features of two rare hepatic conditions, partial nodular transformation, and nodular regenerative hyperplasia. The angiographic findings in this caes are strikingly similar to that which has been reported in cases of idiopathic portal hypertension.

Adult↗
PubMedDate not supplied

Acetaminophen hepatotoxicity: An update.

Acetaminophen is a widely used nonprescription analgesic and antipyretic agent. It is also a dose-related hepatotoxin that can cause fulminant liver failure when taken in massive overdoses or, much less commonly, at therapeutic doses in susceptible individuals. Persons who regularly consume alcohol or persons who have been fasting may be more susceptible to this hepatotoxicity. This liver injury is due not to the drug itself but to the formation of the toxic metabolite N-acetyl-p-benzoquinine imine generated through the cytochrome P-450 drug-metabolizing system. Normally, hepatic stores of glutathione combine with the toxic metabolite and prevent liver cell injury. When glutathione stores are depleted by overproduction of this metabolite, however, the reactive metabolite binds to liver cell proteins and causes hepatic necrosis. P-450 2E1 is induced by alcohol consumption and possibly starvation, and glutathione depletion can occur due to the inadequate nutrition occurring in chronic alcohol use or in starvation. Recent studies have shown that activated Kupffer cells and their secreted toxic agents such as cytokines may also play a role in this liver injury. This liver injury is characterized by extremely high levels of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (> 1000), and bad prognostic signs include severe prolongation of the prothrombin time, renal dysfunction, and, most importantly, acidosis. N-acetylcysteine is a highly effective antidote when given early (within 15 hours) of overdose. Some patients may develop such fulminant liver injury that they require transplantation. Unfortunately, many such patients have a course so rapid that a donor liver may not become available in time. Thus, both the medical community and the general public require a heightened understanding of this clinical problem in order to initiate prevention measures and to implement early therapeutic measures if an overdose situation occurs.

Acetaminophen↗