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Biomedical subjects

W Spivak

Publications and source records attributed to W Spivak.

At least 19 recordsLinked to original sources
PubMed2001

Cyclosporine-Induced neurotoxicity during treatment of Crohn's disease: lack of correlation with previously reported risk factors.

A 13-yr-old boy with severe Crohn's disease was admitted with persistent hematochezia requiring transfusion. Cyclosporine A was begun on hospital day 22 because of continued diarrhea and rectal bleeding despite high doses of i.v. corticosteroids. Six days into cyclosporine therapy, the patient developed multiple episodes of generalized tonic-clonic seizures accompanied with magnetic resonance imaging findings typical, although not pathognomonic, of cyclosporine A central nervous system neurotoxicity. Further investigations demonstrated that severe cyclosporine neurotoxicity may occur in the absence of previously reported clinical risk factors. Experience from the pediatric and adult GI transplant and neurological literature is discussed.

Adolescent↗
PubMed1995

The relationship between insurance class and severity of presentation of inflammatory bowel disease in children.

OBJECTIVE: To determine whether there is an association between insurance class and the severity of presentation of inflammatory bowel disease in children. METHODS: Twenty underinsured (either no insurance or Medicaid) children were computer-matched with 20 children with private insurance with regard to diagnosis and age but without regard to severity of disease from a pool of 63 patients (20 underinsured patients and 43 insured patients). We compared four patient-reported parameters and eight laboratory values. RESULTS: There were 22 patients with Crohn's disease (11 underinsured and 11 insured) and 18 patients with ulcerative colitis (nine underinsured and nine insured), with a mean age at diagnosis of 13.7 +/- 4.2 yr in the underinsured and 13.4 +/- 3.8 yr in the privately insured patients. Patients in the underinsured category had more than 2.5 times the weight loss of the privately insured patients (20.0 +/- 13.9 vs. 7.8 +/- 8.6, p < 0.005) and longer delay in months (10.3 +/- 10.9 vs. 2.7 +/- 2.6, p < 0.005) before the diagnosis was made. Laboratory data in the underinsured children indicated that they were more ill at time of presentation than the insured patients. The underinsured patients had significantly lower hemoglobins (10.5 +/- 2.4 vs. 12.5 +/- 2.1, p < 0.01), a higher erythrocyte sedimentation rate (59 +/- 35 vs. 21 +/- 24, p < 0.005), and higher platelet counts (536 +/- 205 x 10(3) vs. 418 +/- 140 x 10(3), p < 0.05) compared to the insured group. Alkaline phosphatase levels, normally elevated in children during osseous growth, were significantly depressed in the underinsured group when compared with the insured group (117 +/- 42 vs. 155 +/- 71, p = 0.05). CONCLUSION: Underinsured children have clinical and laboratory parameters that indicate that their disease is more severe at presentation than privately insured patients. We postulate that this is partly related to the fact that underinsured patients have inferior access to quality healthcare when compared to privately insured patients.

Adolescent↗
PubMed1994

Neonatal cholestasis. New approaches to diagnostic evaluation and therapy.

Neonatal cholestasis remains a major diagnostic challenge despite increasing knowledge regarding its pathogenesis. The time constraint and urgency in the investigational process is underscored by the age-dependent success rate of the surgical corrective procedures for EHBA. Appropriate interpretation of imaging and pathologic studies requires a pediatric center familiar with the entities causing neonatal cholestasis. When liver failure or progressive hepatic dysfunction is likely to occur, early referral to a liver transplant center is recommended. Despite the increasing experience and excellent results of pediatric liver transplantation, at this point, surgical corrective procedures such as the Kasai procedure remain the first line of treatment for most patients with EHBA.

Cholestasis↗
PubMed1993

Evaluation of cavernous transformation of the portal vein by magnetic resonance imaging.

We describe two children who underwent magnetic resonance imaging (MRI) as part of the evaluation of isolated splenomegaly after Doppler ultrasound was unable to identify the portal vein. The diagnosis of cavernous transformation of the portal vein and the normalcy of the biliary tract and hepatic architecture were confirmed by MRI. Because of the risks associated with computed tomography (CT) and angiographic evaluation of such patients, the use of MRI, a noninvasive modality, in the evaluation of pediatric patients requires further consideration.

Angiography↗
PubMed1990

Critical self-association of bile lipids studied by infrared spectroscopy and viscometry.

Fourier transform infrared (FTIR)-attenuated total reflection (ATR) spectroscopy and viscometry were applied to study the micellization of two bile lipids, sodium taurochenodeoxycholate (NaTCDC) and sodium glycocholate (NaGC), in aqueous solutions. The CH2 stretching bands of the bile lipid hydrocarbon region were shifted to higher frequencies suggesting initial critical micellization at 2.5 mM for NaTCDC and 9 mM for NaGC. An abrupt enhancement of the absorption intensity of the CH3 groups of the sterol rings in bile lipids were under conformational strain at 3.5 mM NaTCDC and 9 mM NaGC. Viscometry measurements showed abrupt changes in viscosities in the region of critical micellar concentration (CMC) of both bile lipids. Both infrared and viscometry studies confirmed the onset of conformational strains in tightly packed lipid micelles at their CMC. In addition, FTIR/ATR spectroscopy has defined the specific hydrophobic interactions which bring about critical micellization of bile lipids.

Bile↗
PubMed1988

Spectrophotometric determination of the critical micellar concentration of bile salts using bilirubin monoglucuronide as a micellar probe. Utility of derivative spectroscopy.

We have developed a simple biologically non-invasive method for determining the critical micellar concentration (CMC) of bile salts using pure naturally occurring bilirubin IX alpha monoglucuronide (BMG), an important bile pigment present in virtually all mammalian biles. This methodology employs visible absorbance spectroscopy of BMG in bile salts over a range of bile salt concentrations that include the reported CMC. Using 100 microM-BMG in 0.4 M-imidazole buffer at pH 7.8, we calculated that the CMC for sodium taurochenodeoxycholate is between 2.5 and 3.0 mM based on: (1) an abrupt change in lambda max. in this concentration range, (2) a precipitous decrease in the amplitude of the absorbance shoulder at 450 nm, (3) a sudden decrease in the second derivative absorbance of BMG at 400 nm and an increase in absorbance at 470 nm, (4) a sharp change in the 4th derivative absorbance at 375 and 395 nm. In contrast, sodium taurocholate, a bile salt that reportedly does not have a CMC but continuously self-associates over a wide concentration range, exhibited none of these changes. The use of derivative spectroscopy enhances the ability to detect the CMC changes and also indicates the number of BMG species in solution and their relative energy states.

Bilirubin↗
PubMed1987

Non-enzymic hydrolysis of bilirubin mono- and diglucuronide to unconjugated bilirubin in model and native bile systems. Potential role in the formation of gallstones.

Pigment gallstones contain considerable amounts of unconjugated bilirubin (UCB) in the form of calcium bilirubinate and/or bilirubin polymers. Since more than 98% of bile pigments are excreted as conjugates of bilirubin, the source of this UCB needs to be identified. By using a rapid h.p.l.c. method, we compared the non-enzymic hydrolysis of bilirubin monoglucuronide (BMG) and bilirubin diglucuronide (BDG) to UCB in model bile and in native guinea-pig bile. Model biles containing 50 microM solutions of pure BMG and BDG were individually incubated in 25 mM-sodium taurocholate (NaTC) and 0.4 M-imidazole/5 mM-ascorbate buffer (TC-BUF) at 37 degrees C. Over an 8 h period, BMG hydrolysis produced 4-6 times more UCB than BDG hydrolysis. At pH 7.4, 25% of the BMG was converted into UCB, whereas only 4.5% of BDG was converted into UCB. Hydrolysis rates for both BMG and BDG followed the pH order 7.8 greater than 7.6 approximately equal to 7.4 greater than 7.1 Incubation with Ca2+ (6.2 mM) at pH 7.4 in TC-BUF resulted in precipitated bile pigment which, at 100 X magnification, appeared similar to precipitates seen in the bile of patients with pigment gallstones. At pH 7.4, lecithin (crude phosphatidylcholine) (4.2 mM) was a potent inhibitor of hydrolysis of BMG and BDG. The addition of a concentration of cholesterol equimolar with that of lecithin eliminated this inhibitory effect. Guinea-pig gallbladder bile incubated with glucaro-1,4-lactone (an inhibitor of beta-glucuronidase) underwent hydrolysis similar to the model bile systems. The non-enzymic hydrolysis of bile pigments, especially BMG, may be an important mechanism of bile-pigment precipitation and, ultimately, of gallstone formation.

Animals↗
PubMed1987

Diagnostic utility of hepatobiliary scintigraphy with 99mTc-DISIDA in neonatal cholestasis.

We retrospectively evaluated the utility of hepatobiliary scintigraphy and various clinical factors in differentiating intrahepatic cholestasis from biliary atresia in 28 consecutive infants with neonatal cholestasis. One millicurie of technetium-labeled diisopropyliminodiacetic acid (DISIDA) was administered intravenously, and images were obtained for up to 24 hours or until gastrointestinal excretion was noted. Nine separate studies in seven infants with biliary atresia were correctly interpreted as showing no gastrointestinal excretion of radionuclide. Of the 21 patients with intrahepatic cholestasis, only nine had gastrointestinal excretion on the first study; in eight without excretion, a second study was done, and five of these showed gut excretion. All infants with either neonatal hepatitis (six) or inspissated bile syndrome (three) had demonstrable gastrointestinal excretion either on the first or second DISIDA study. However, five of six infants with paucity of intrahepatic bile ducts, two of six infants with cholestasis secondary to total parenteral nutrition, and one infant with cholangiolitis did not show evidence of gastrointestinal excretion. The mean birth weight, mean gestational age, and mean weight at study were significantly greater (P less than 0.005) for infants with biliary atresia without excretion than for infants with intrahepatic cholestasis without excretion. The mean direct bilirubin concentration was 6.0 mg/dL for both infants with biliary atresia and infants with intrahepatic cholestasis without excretion; however, infants with excretion had a significantly lower (P less than 0.02) mean direct bilirubin value of 3.4 mg/dL. Excretion was noted in four infants with total bilirubin values greater than 10.0 mg/dL. The absence of gut excretion on the first DISIDA study was 100% sensitive but only 43% specific for biliary atresia. In infants without gut excretion of DISIDA, birth weight greater than 2200 g was 100% sensitive and 92% specific for biliary atresia. We conclude that DISIDA scanning, together with clinical data, is useful in differentiating extrahepatic from intrahepatic cholestasis. The absence of gut excretion on the first DISIDA study does not necessarily indicate extrahepatic obstruction; the study should be repeated if the diagnosis is not clear.

Bile Ducts, Intrahepatic↗
PubMed1986

Application of a rapid and efficient h.p.l.c. method to measure bilirubin and its conjugates from native bile and in model bile systems. Potential use as a tool for kinetic reactions and as an aid in diagnosis of hepatobiliary disease.

We have developed an extremely rapid and efficient reverse-phase h.p.l.c. method for the measurement of bilirubin and its conjugates in human bile and in model bile systems. Our method involves the use of a Perkin-Elmer 3 mu C18 column and a methanol/sodium acetate/aq. ammonium acetate buffer system. Three isomers of bilirubin diglucuronide (BDG), two isomers of bilirubin monoglucuronide (BMG), three isomers of unconjugated bilirubin (UCB) and minor conjugates containing glucose and xylose were separated in 12 min. Initial quantification of BDG and BMG was based on the use of the ethyl anthranilate azo derivative of bilirubin (AZO UCB); however, the standard curves for BDG, BMG and UCB were similar enough to permit quantification to be later based on the UCB standard curve only, thereby simplifying the quantification process. Routine direct injection of 6 or 10 microliter of crude undiluted or diluted (1:1) bile sample was sufficient for analysis. The method was helpful in diagnosing biliary-tract obstruction in a newborn and a partial deficiency state of bilirubin conjugation (Crigler-Najjar syndrome) in a 10-year-old male. When the method was applied to biles of patients both with and without gallstones, levels of UCB were less than 2% of total pigment, consistent with previous reports. Because of its speed and efficiency, this method has the potential for a broad range of applications including enzymic, kinetic and bile sample analyses.

Animals↗
PubMed1985

Reverse-phase h.p.l.c. separation, quantification and preparation of bilirubin and its conjugates from native bile. Quantitative analysis of the intact tetrapyrroles based on h.p.l.c. of their ethyl anthranilate azo derivatives.

We describe a facile and sensitive reverse-phase h.p.l.c. method for analytical separation of biliary bile pigments and direct quantification of unconjugated bilirubin (UCB) and its monoglucuronide (BMG) and diglucuronide (BDG) conjugates in bile. The method can be 'scaled up' for preparative isolation of pure BDG and BMG from pigment-enriched biles. We employed an Altex ultrasphere ODS column in the preparative steps and a Waters mu-Bondapak C18 column in the separatory and analytical procedures. Bile pigments were eluted with ammonium acetate buffer, pH 4.5, and a 20 min linear gradient of 60-100% (v/v) methanol at a flow rate of 2.0 ml/min for the preparative separations and 1.0 ml/min for the analytical separations. Bile pigments were eluted in order of decreasing polarity (glucuronide greater than glucose greater than xylose conjugates greater than UCB) and were chemically identified by t.l.c. of their respective ethyl anthranilate azo derivatives. Quantification of UCB was carried out by using a standard curve relating a range of h.p.l.c. integrated peak areas to concentrations of pure crystalline UCB. A pure crystalline ethyl anthranilate azo derivative of UCB (AZO . UCB) was employed as a single h.p.l.c. reference standard for quantification of BMG and BDG. We demonstrate that: separation and quantification of biliary bile pigments are rapid (approximately 25 min); bile pigment concentrations ranging from 1-500 microM can be determined 'on line' by using 5 microliters of bile without sample pretreatment; bilirubin conjugates can be obtained preparatively in milligram quantities without degradation or contamination by other components of bile. H.p.l.c. analyses of a series of mammalian biles show that biliary UCB concentrations generally range from 1 to 17 microM. These values are considerably lower than those estimated previously by t.l.c. BMG is the predominant, if not exclusive, bilirubin conjugate in the biles of a number of rodents (guinea pig, hamster, mouse, prairie dog) that are experimental models of both pigment and cholesterol gallstone formation. Conjugated bilirubins in the biles of other animals (human, monkey, pony, cat, rat and dog) are chemically more diverse and include mono-, di- and mixed disconjugates of glucuronic acid, xylose and glucose in proportions that give distinct patterns for each species.

Animals↗
PubMed1984

Effects of halothane anesthesia on equine liver function.

Effects of halothane anesthesia were investigated in ponies prepared surgically with chronic external biliary fistulas (T tubes) to determine the effects on liver function and biliary excretion during 2 hours of anesthesia. Four studies were performed on 2 ponies, 2 to 6 months after surgery with the enterohepatic circulation held intact between studies. Intravenous bile acid infusion was used to maintain steady-state bile flow, bilirubin, and bile acid excretion during each study. Compared with the immediate 2-hour preanesthesia values (base line), halothane caused a 138% increase in bilirubin excretion, a 60% increase in biliary bilirubin concentration, and a 43% increase in PCV. Halothane anesthesia also caused a 16% reduction in plasma bilirubin, a 46% reduction in biliary bile acid concentration, and a 27% reduction in bile acid excretion. The bile acid independent fraction of bile flow appeared to increase. Plasma aspartate transaminase concentration did not change during anesthesia. The ratio of conjugated bilirubin fractions in bile [82% to 83% disconjugates of glucuronide and glucoside (2 forms) and 17% to 18% monoconjugates of glucoside, glucuronide, and xyloside] did not change during anesthesia and less than 1% was excreted unconjugated. Halothane anesthesia did not appear to affect adversely the activity of the transferase-conjugating enzymes in the presence of an increased bilirubin load. Seemingly, greatly increased conjugated bilirubin excretion observed during halothane anesthesia was most likely the result of a combination of increased hepatic clearance from plasma and increased hepatic bilirubin production from turnover of free hepatic heme or heme from the induced cytochrome P-450 system.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1983

General configuration of cholestasis in the newborn.

The infant with cholestasis presents a series of diagnostic challenges which require careful delineation. Correct diagnosis, permitting selection of appropriate management and therapy, can be made in the vast majority of patients. When the diagnosis remains obscure, exploratory surgery to distinguish intrahepatic from extrahepatic cholestasis should be performed by 60 days of age in order to provide the best possible outcome. Nevertheless, in both intrahepatic and extrahepatic cholestatic disorders, the characteristics of the original insult determine the prognosis, which may often be predicted by the early liver biopsy. When end-stage liver disease is inevitable, hepatic transplantation may be considered.

Bacterial Infections↗
PubMed1975

Benzopyranopyridine derivatives. 1. Aminoalkyl derivatives of the azaxanthenes as bronchodilating agents.

The preparation of the four isomeric azaxanthones 3 and a number of their aromatic ring substituted derivatives is described. These ketones were converted into the title compounds which were examined for their biological properties. The most interesting compound in this series, the 1-methyl-4-piperidylidene derivative of 1-azaxanthene, shows the profile of an orally effective potent bronchodilating agent as well as a moderate antihistamine. Biological properties of this compound were compared to a number of antihistamines as well as known bronchodilating agents. Structure-activity relationships are also discussed.

Airway Resistance↗