Interference of zinc heparin anticoagulant in determination of plasma magnesium.
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Anticoagulants↗
Biomedical subjects
C H Smith
Publications and source records attributed to C H Smith.
Neuropeptides induce rapid expression of endothelial cell adhesion molecules and elicit granulocytic infiltration in human skin.
Inflammatory cell infiltrates and cell adhesion molecule expression have been examined in normal human skin after intradermal injection of sensory neuropeptides substance P (n = 6), vasoactive intestinal polypeptide (n = 6), and calcitonin gene-related peptide (n = 6) together with PBS as control (n = 4). Each neuropeptide induced rapid, time-dependent neutrophil influx into dermis, which was initially observed at 15 min and persisted for 8 h after injection. Increases in numbers of neutrophils with time after substance P, vasoactive intestinal polypeptide and calcitonin gene-related peptide were highly significant when compared with controls p < 0.005, p < 0.005, p < 0.005, respectively (analysis of variance). Substance P additionally induced marked eosinophilic accumulation at 4 and 8 h in four of six subjects. These changes paralleled rapid translocation of P-selectin from cytoplasmic Weibel-Palade granules to luminal membranes by 15 min, and significant up-regulation of E-selectin expression at 4 and 8 h. Increases in percentage of E-selectin positive vessels with respect to time after each neuropeptide were highly significant when compared with controls, p < 0.005, p < 0.005, p < 0.005 (ANOVA), respectively, and were significantly correlated with neutrophil infiltrates, r = 0.55, p < 0.001. VCAM-1 was not expressed, and constitutive ICAM-1 expression on dermal endothelium was unchanged at all time points examined (0-8 h). Induction of endothelial adhesion molecule expression by neuropeptides provides a mechanism for neutrophil accumulation in neurogenic inflammation. Substance P-induced eosinophil accumulation in the absence of VCAM-1 expression suggests that mechanisms distinct from VCAM-1/very late antigen-4 binding mediate selective tissue eosinophilia.
Adult↗
Excess melanocytic nevi in children with renal allografts.
BACKGROUND: Renal allograft transplantation is associated with an increased incidence of malignant melanoma. The development of excess melanocytic nevi may be an indicator of this risk. OBJECTIVE: This study determines the prevalence of melanocytic nevi in children who have received renal allografts. METHODS: Total and regional melanocytic nevi counts were made in 38 children (27 boys, 11 girls) with a renal allograft and in 38 individually age- and sex-matched healthy controls; counts were related to age, sex, skin type, and duration of immunosuppression. RESULTS: There was a significant increase in the total number of nevi in the renal transplant group compared with the control group (p < 0.05), with most marked increases occurring on the back and at acral sites. A strong positive correlation between nevi count and duration of immunosuppression independent of age was observed (p < 0.005). CONCLUSION: Excess numbers of melanocytic nevi occur in children with renal allografts. These patients constitute a risk group for malignant melanoma and require continued assessment.
Adolescent↗
Do cats in New Zealand with renal failure require potassium supplementation?
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Letter↗
A case of chromoblastomycosis responding to treatment with itraconazole.
Chromoblastomycosis is a rare, chronic, cutaneous infection caused by a group of dematiacaeous fungi. We report a case which, in addition to characteristic clinical and histopathological features of chromoblastomycosis, displayed atypical, deep dermal/subcutaneous involvement, and showed a good response to itraconazole.
Antifungal Agents↗
The relative importance of extracellular and intracellular calcium in the responses of the human vas deferens to noradrenaline and potassium: a study using Ca(2+)-deprivation and Ca(2+)-antagonists.
1. Mechanical responses of the human vas deferens, activated by noradrenaline (50-100 microM) or high potassium (130 mM), showed either biphasic shortening or lengthening or a combination of initial shortening and lengthening. These are interpreted as representing the contractions of longitudinal and circular muscle respectively. 2. Caffeine (10-20 mM) induced only shortening responses which were 86% (SE 34, n = 7) of that caused by noradrenaline (100 microM). 3. The calcium channel antagonists, nifedipine, verapamil and diltiazem (0.01-10 microM), inhibited responses to high potassium, and the initial phase of shortening and lengthening responses to noradrenaline. However, the secondary phase of the shortening response to noradrenaline (100 microM) was relatively insensitive to these antagonists. 4. In calcium-free (1 mM EGTA) media, noradrenaline (100 microM) could repeatedly induce both shortening and lengthening tonic responses which were 39 +/- 13% (n = 4) and 40 +/- 16% (n = 5) of their values in Krebs media. Except for a small shortening, responses to high potassium were abolished. Calcium-free media also blocked phasic bursts of mechanical activity. 5. Calcium removal during a prolonged exposure to noradrenaline (50 microM) caused a fall of tension of the lengthening but not the shortening response. Depletion of intracellular stores caused an inhibition of the responses to noradrenaline. Recovery of responses following restoration of calcium was blocked by nifedipine for the shortening response but not for lengthening. 6. We conclude that longitudinal and circular muscle rely to different degrees on activation by extracellular calcium and intracellular mechanisms. The longitudinal, but not circular, muscle appears mainly to use an intracellular calcium pool which is replenished via nifedipine-sensitive calcium channels and has a caffeine sensitive store. Evidence suggesting differences in the role of calcium and processes controlling its entry during activation of both muscle types is presented and discussed.
Caffeine↗
ASC system activity is altered by development of cell polarity in trophoblast from human placenta.
Pathways of neutral amino acid uptake were investigated in vitro during differentiation of primary cultures of trophoblast isolated from full-term human placentas and a clone (b30) of the BeWo cell line. Inhibition of initial alanine (0.1 microM) uptake by 2-(methylamino)isobutyric acid and unlabeled alanine revealed two Na(+)-dependent systems and one Na(+)-independent transporter. Characterization of these transporters, by selective inhibition, suggested system A, ASC, and L-like transporters. Concomitant with formation of microvillous membrane and syncytium, system ASC activity decreased from 16.1 +/- 2.8 pmol.mg DNA-1.min-1 at 24 h to 2.4 +/- 1.1 pmol.mg DNA-1.min-1 at 72 h. Na(+)-independent alanine uptake increased from 6.0 +/- 2.0 to 12.9 +/- 0.9 pmol.mg DNA-1.min-1 at 24 and 72 h, respectively. Similarly, alpha-(methylamino)isobutyric acid-insensitive, Na(+)-dependent activity in b30 cells (100 microM alanine) decreased from 6.5 +/- 1.6 to 1.2 +/- 1.2 nmol.mg DNA-1.min-1 for control and forskolin-treated cells, respectively. We conclude that membrane specialization accompanying fusion and differentiation of the cytotrophoblast to form syncytiotrophoblast results in a polarization of neutral amino acid transport systems.
Alanine↗
Adhesion molecules in allergic inflammation.
Allergic inflammation is characterized by recruitment of specific leukocyte subpopulations from blood into tissue and requires a series of cell adhesion-molecule-mediated interactions between postcapillary vascular endothelium and the leukocyte cell surface. Three major groups are involved: selectins, integrins, and the immunoglobulin gene superfamily. P- and E-selectin mediate initial leukocyte adhesion, whereas beta 2-integrin/ICAM-1 and VLA-4/VCAM-1 pathways mediate leukocyte arrest and transendothelial migration. Because VLA-4 expression is restricted to eosinophils and lymphocytes, VCAM-1 has been implicated in selective eosinophil recruitment characterizing allergic inflammation. However, additional factors such as profile of cytokine release are likely to operate since tissue eosinophilia has been observed in the absence of VCAM-1 expression. Recent use of monoclonal antibodies against functional epitopes on various cell adhesion molecules in animal models of extrinsic allergic asthma offers new possibilities in management of allergic disease.
Animals↗
Automated enzymatic analysis of inulin.
We have developed an automated enzymatic assay for quantitation of inulin in plasma and urine that can be performed on the Cobas FARA II. In the assay, inulinase hydrolyzes inulin to fructose, and sorbitol dehydrogenase converts fructose to sorbitol with consumption of NADH, which is detected by spectrophotometry. The method incorporates a sample blank (inactivated inulinase) for each specimen to subtract contributions of endogenous fructose. Recovery of fructose or inulin was near 100%, with linearity to 300 mg/L. The enzymatic assay (y) agreed well with an anthrone comparison method (x) for analysis of inulin in both urine specimens (y = 1.00x - 138; Sy/x = 714) and plasma specimens (y = 1.00x - 3.5; Sy/x = 5.5). Glucose at 300 mg/L yielded an apparent inulin value of 1.3 mg/L in the enzymatic assay, but reacted at nearly 10% equivalency in the anthrone assay. Interferences from sorbitol, mannitol, and xylitol were negligible. CVs for day-to-day precision studies were 1-4%. The automated enzymatic assay of inulin is faster and avoids the use of caustic reagents required by the classical anthrone method.
Anthracenes↗
Idiopathic hypertrophic cranial pachymeningitis.
We evaluated 3 patients with biopsy-proven hypertrophic cranial pachymeningitis apparently unrelated to any systemic disease. Each patient had chronic headache, cranial neuropathy, an elevated ESR, and a mild CSF pleocytosis. Neuro-ophthalmic findings included bilateral sixth nerve palsies in two patients and the third had bilateral optic neuropathies. MR imaging revealed thickened dura that enhanced with Gd-DTPA administration. Histologic examination showed thickened, fibrotic dura with a sterile, chronic, nongranulomatous inflammation. The response to treatment was variable with corticosteroids, immunosuppressive drugs, or radiation. The distinctive MR appearance should help physicians recognize this rarely reported disease.
Abducens Nerve↗
Evaluation of evacuated blood-collection tubes: effects of three types of polymeric separators on therapeutic drug-monitoring specimens.
The potential of three types of separator materials found in conventional blood-collection tubes for interference in therapeutic drug measurements was assessed. None of the separators (based on acrylic, silicone, or polyester polymers) had any significant effect on the concentrations of seven drugs (theophylline, digoxin, phenytoin, phenobarbital, gentamicin, ethanol, and cyclosporine) in blood specimens that were processed and analyzed promptly. Storage of specimens for 24 h resulted in an average 2.4% increase in theophylline values in specimens collected in tubes with the acrylic separator (P = 0.024); an average 8.1% decrease in phenytoin in specimens collected in tubes with the polyester-based separator (P < 0.001); and an average 4.2% decrease in phenobarbital in specimens collected in tubes with the polyester-based separator (P = 0.02). All other drug concentrations were not significantly affected. A small decrease in phenytoin (7.9%; P < 0.01) was seen when the specimen volume in 7-mL tubes containing polyester-based separator was reduced to 1.0 mL; all other drug concentrations were unaffected by partial filling of tubes. Paired blood specimens from pediatric patients, when collected in plain tubes and tubes containing acrylic separator, yielded no significant differences for theophylline, digoxin, tobramycin, phenytoin, or phenobarbital concentrations. The three commercially available separators had only small effects on therapeutic drug concentrations, and a newly developed separator based on an acrylic resin was suitably inert.
Acrylic Resins↗
Human placental syncytiotrophoblast expresses two pharmacologically distinguishable types of Na(+)-H+ exchangers, NHE-1 in the maternal-facing (brush border) membrane and NHE-2 in the fetal-facing (basal) membrane.
We investigated whether highly purified preparations of basal (fetal-facing) membrane isolated from normal term human placentas possess Na(+)-H+ exchanger activity. Uptake of Na+ into basal membrane vesicles was stimulated many-fold by an outwardly directed H+ gradient. This H(+)-gradient-dependent uptake was inhibitable by amiloride and its analogues. Na+ uptake in these vesicles did not occur via a Na+ channel, as it was not influenced by changes in membrane potential and, in addition, was inhibited by benzamil only at high micromolar concentrations. The results indicate that the human placental basal membrane possesses Na(+)-H+ exchanger activity. We then studied whether this exchanger is similar to or distinct from the Na(+)-H+ exchanger described in brush border (maternal-facing) membrane preparations. For this purpose, we compared the pharmacological characteristics of the basal membrane Na(+)-H+ exchanger with those of the brush border membrane Na(+)-H+ exchanger. The basal membrane exchanger was about 20-fold less sensitive to inhibition by amiloride and about 70-fold less sensitive to inhibition by dimethylamiloride than was the brush border membrane exchanger. The exchanger activity in both membrane preparations was inhibitable by clonidine and cimetidine, but the inhibition patterns with these compounds were markedly different between basal and brush border membrane preparations. These data demonstrate that the basal membrane Na(+)-H+ exchanger is distinct from the brush border membrane Na(+)-H+ exchanger. The pharmacological profiles of these exchangers indicate that the human placental brush border membrane possesses the housekeeping or non-epithelial type Na(+)-H+ exchanger (NHE-1), whereas the basal membrane possesses the epithelial or apical type Na(+)-H+ exchanger (NHE-2).
Basement Membrane↗
Cutaneous responses to vasoactive intestinal polypeptide in chronic idiopathic urticaria.
Cutaneous wheal and flare responses to increasing concentrations of calcitonin gene-related peptide, substance P, neurokinin A, vasoactive intestinal polypeptide (VIP), compound 48/80, and phosphate-buffered saline were measured in 10 patients with chronic idiopathic urticaria and 10 healthy controls. A significant increase in VIP-induced wheal, but not flare or cutaneous blood flow, was seen in urticarial patients compared with controls (p less than 0.001). No significant differences in responses to other tested compounds were found between these groups. These data point to an increased sensitivity of microvasculature to VIP in patients with chronic idiopathic urticaria.
Adult↗
Cutaneous histamine metabolism in chronic urticaria.
Impaired metabolism of histamine in the skin of patients with chronic idiopathic urticaria (CIU) might explain the observed enhanced and prolonged skin responses to intradermal histamine. Histamine metabolism was measured in homogenates from unaffected forearm skin in nine patients with CIU and in skin of age- and sex-matched control subjects with a radiochromatographic assay, and the results are expressed as nanograms of histamine metabolized per milligram of protein per hour. Endogenous histamine content was determined by RIA. There was a highly significant increase in endogenous histamine content in the skin of patients with urticaria (407.8 +/- 188.3 ng/mg of protein) compared with that in skin of control subjects (240.0 +/- 73.0 ng/mg of protein) (mean +/- 1 SD; p less than 0.02), which suggests either an increase in mast cell number or histamine concentration per cell. No significant difference was observed in the metabolism of histamine between patient and control group; therefore, an alternative mechanism may underlie differences in skin reactivity to histamine.
Chronic Disease↗
Nutrient transport pathways across the epithelium of the placenta.
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Amino Acids↗
Transport and binding in calcium uptake by microvillous membrane of human placenta.
Calcium entry across the microvillous membrane of the human placental syncytiotrophoblast is the first step in the transfer of this important nutrient to the fetus. Calcium uptake by isolated microvillous membranes was time dependent. Equilibrium uptake was very much greater than could be explained by equilibration of the vesicle space with medium, indicating that calcium is bound to internal sites. Addition of the ionophore A23187 greatly increased the rates of influx and efflux, indicating that transport across the plasma membrane is rate limiting in entry. Concentration dependence data for calcium transport at 4 s fit well to a Michaelis-Menten equation having two saturable sites and diffusion. Calcium entry by both transporters was unaffected by calcium channel blockers but was strongly inhibited by the group II metals. The distinct inhibition constant values for strontium inhibition provided additional evidence for two transporters. Calcium binding fit well to a single-site model saturable in the micromolar range. In vivo, the saturable transport processes may mediate calcium entry into the syncytiotrophoblast and binding may regulate concentration within the placental microvilli.
Barium↗
Macroamylases: differences in activity against various-size substrates.
Hyperamylasemia caused by macroamylases can lead to the overdiagnosis of acute pancreatitis. We examined whether interference from macroamylase is less in assays that use high-molecular-weight rather than oligosaccharide substrates. We hypothesized that high-molecular-weight substrates would be sterically excluded from macroamylasemic complexes and thus would be hydrolyzed less efficiently. Eighteen macroamylasemic samples were assayed by using red-dyed amylopectin or blue-dyed starch as polysaccharide substrates or by using maltoheptaose or maltotetraose as oligosaccharide substrates. The oligosaccharide substrates gave comparable results (y = 0.81x + 83); we observed consistently lower activities for amylopectin than for maltotetraose (y = 0.32x + 38). We observed no bias among methods when nonmacroamylasemic specimens were analyzed. The mechanism of this difference was examined by adding anti-human pancreatic amylase antibodies to hyperamylasemic serum samples from patients without macroamylasemia and purified human pancreatic or salivary isoamylases. In each case, polyclonal and monoclonal antibodies lowered amylase activity more in assays with complex polysaccharides than in those with oligosaccharides. The use of high-molecular-weight substrates diminishes interference, and detection of suspected macroamylasemia may be possible through comparison of activities determined from automated methods that use different substrates.
Amylases↗
Macroamylases: differences in activity against various-sized substrates.
Hyperamylasemia caused by macroamylases can lead to the overdiagnosis of acute pancreatitis. We examined whether interference from macroamylase is less in assays that use high-molecular-mass (high-M(r)) substrates rather than oligosaccharide substrates. We hypothesized that high-M(r) substrates would be sterically excluded from macroamylasemic complexes and thus would be hydrolyzed less efficiently. Eighteen macroamylasemic samples were assayed by using red-dyed amylopectin or blue-dyed starch as polysaccharide substrates or by using maltoheptaose or maltotetraose as oligosaccharide substrates. The oligosaccharide substrates gave comparable results (y = 0.81x + 83), but we observed consistently lower activities for amylopectin than for maltotetraose (y = 0.32x + 38). We observed no bias among methods when nonmacroamylasemic specimens were analyzed. The mechanism of this difference was examined by adding antihuman pancreatic amylase antibodies to hyperamylasemic serum samples from patients without macroamylasemia and to purified human pancreatic or salivary isoamylases. In each case, polyclonal and monoclonal antibodies lowered amylase activity more in assays with complex polysaccharides than in those with oligosaccharides. The use of high-M(r) substrates diminishes interference, and detection of suspected macroamylasemia may be possible through comparing activities determined from automated methods that use different substrates.
Amylases↗