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S L Perkins

Publications and source records attributed to S L Perkins.

At least 91 records · Page 5Linked to original sources
PubMed1991

High-performance liquid-chromatographic method compared with a modified radioimmunoassay of cotinine in plasma.

Cotinine is a sensitive and specific biochemical marker of exposure to cigarette smoke. We describe a simple solid-phase extraction of cotinine from plasma before quantification by HPLC. Extraction recovery was 97.9% +/- 11.0% for plasma concentrations of 5-400 micrograms/L. Baseline separation of cotinine and caffeine was achieved within 11 min of injection onto a C18 reversed-phase column. The mobile phase was citric acid/dibasic potassium phosphate (30 mmol/L each, pH 6.0) containing 100 mL of acetonitrile per liter. Within-day and day-to-day precision (CV) were 4.7% and 8.4%, respectively. We also describe a modification of the Nicotine Metabolite RIA kit (Diagnostic Products Corp.) for quantifying cotinine in plasma. Recovery of cotinine from supplemented plasma was within 10% of the expected value with this RIA kit. Interassay precision averaged 8.1% for samples in the range 50-400 micrograms/L; intra-assay precision averaged 3.6% at 230 micrograms/L and 8.7% at 53 micrograms/L. Correlation between the two methods was RIA = 1.13 HPLC + 14.8 (n = 128, r = 0.957, P less than 0.001). Both methods are technically simple to perform.

Chromatography, High Pressure Liquid↗
PubMed1990

Prostaglandin E specifically upregulates the expression of the mannose-receptor on mouse bone marrow-derived macrophages.

The macrophage mannose receptor (MMR) facilitates the binding and internalization of microorganisms and glycoproteins with terminal mannose residues. The receptor is progressively upregulated as bone marrow precursor cells mature into macrophages and thus may serve as a marker of differentiation. Prostaglandins of the E series (PGE) are known inhibitors of monocyte and macrophage precursor proliferation, an effect often associated with cellular maturation. MMR expression was therefore assessed after exposure of bone marrow macrophage precursor (BMMP) cells to these prostanoids. Receptor expression was determined by ligand binding and via immunoprecipitation of newly synthesized receptor molecules. PGE1 and PGE2 at 10(-9)-10(-6) M upregulated MMR surface expression and biosynthesis four- to sixfold in a dose-dependent manner. BMMPs responsive to prostaglandins were characterized by plastic adherence, F4/80 antigen expression, and nonspecific esterase activity. Prostaglandins accelerated the expression of the MMR in cells by 48-72h, with maximal levels of receptor expression being identical in control or treated cells. Thus, prostaglandins enhanced mannose receptor expression in adherent but not fully differentiated macrophage precursors. This effect is specific for PGE and is mimicked by dibutyrl cyclic AMP. These results indicate that prostaglandins accelerate MMR expression and hence the differentiation of macrophage precursor cells. Cells resident in the bone marrow secrete abundant prostaglandins, suggesting that a paracrine mechanism may exist to regulate MMR expression and function.

Adenylyl Cyclases↗
PubMed1989

Serum human chorionic gonadotrophin levels in early pregnancy.

Serum hCG reference intervals for various gestational periods in normal pregnancies were determined using three commercial assays--two standardized against the WHO 2nd IS (Amersham Amerlex-M beta HCG RIA (AMX) and Abbott beta-HCG 15/15 (ABB] and one standardized against the WHO 1 IRP (Hybritech Tandem -E HCG (HYB]. Serial samples from patients with accurately determined gestational periods were analyzed. We correlated these assays to determine the validity of the common practice of interchanging values between assays using the same WHO standard and of converting 1st IRP values to 2nd IS values by a fixed factor. The slope of correlation between the two 2nd IS assays (AMX, ABB) was 1.43, r = 0.960; whereas between the 1 IRP assay (HYB) and the two 2nd IS assays the slopes were 1.67, r = 0.963 and 1.22, r = 0.971 for AMX and ABB, respectively. In a prospective study of 52 patients with normal pregnancies, serum beta-hCG values in 46% of samples taken at 28-35 days gestation fell below the lower limit of the reference curves supplied with the AMX kit. Ninety-two percent of samples were within the newly established intervals. These results indicate that supplier's reference limits may not be accurate; in addition, a common factor should not be used to convert values from one commercial kit to another.

Adult↗
PubMed1989

Loss of porphyrins from solution during analysis: effect of sample pH and matrix on porphyrin quantification in urine by "high-performance" liquid chromatography.

We report the effect of sample matrix and pH on quantification of porphyrins by HPLC with fluorimetric detection. For aqueous solutions of pH less than 2.5, HPLC peak heights of the porphyrins increased with decreasing pH, reaching a plateau at pH less than 1.0. This loss of porphyrins from solutions with pH greater than 1.0 appeared to be due to a combination of microprecipitation and aggregation effects. No such "pH effect" was observed for urine samples supplemented with mixed-porphyrin standards. Addition of trace amounts of albumin to aqueous solutions also decreased these pH-related losses. These findings suggest a porphyrin-protein interaction that prevents microprecipitation and aggregation processes. We conclude that standard solutions of porphyrins for HPLC analysis should be prepared in a urine matrix. If aqueous solutions are used, then the pH must be adjusted to less than 1.0. Urine samples from normal individuals require only adjustment of pH to less than 2 before analysis; however, porphyric urines requiring dilution should be prepared with porphyrin-free urine diluent.

Chromatography, High Pressure Liquid↗
PubMed1988

Analytical problems encountered during high-performance liquid chromatographic separation and coulometric detection of bopindolol metabolites in human plasma.

Good clinical control of hypertension is achieved with low doses of the potent beta-blocker bopindolol. Pharmacokinetic evaluations therefore require an analytical technique of high sensitivity. Analysis of plasma by high-performance liquid chromatography (HPLC) using electrochemical detection provides this sensitivity. This article describes the development of an analytical procedure and presents a reversed-phase HPLC method with coulometric detection suitable for plasma analyses during pharmacokinetic investigations of bopindolol therapy.

Adrenergic beta-Antagonists↗
PubMed1988

A ceramic glazer presenting with extremely high lead levels.

A case of lead poisoning in a ceramic glazer is reported. The patient had an extremely high level of blood lead at 29.5 mumol/l, and many of the laboratory features of lead toxicity: normocytic anaemia with marked basophilic stippling, abnormal blood and urinary porphyrins, and elevated liver enzymes. Surprisingly, the patient had no electromyographic evidence of neurologic involvement. The patient was treated with intravenous EDTA-calcium followed by oral penicillamine. Urinary porphyrin and porphyrin precursor excretion followed an interesting pattern, correlating with the chelator used. This patient illustrates that extremely high blood lead level can be achieved through the oral route in an adult.

Adult↗
PubMed1988

A high-speed liquid-chromatographic method for measuring urinary porphyrins.

We describe a rapid quantitative and qualitative "high-performance" liquid-chromatographic (HPLC) method for measuring porphyrins in urine. Direct injection of acidified, filtered urine onto a 3-micron (particle size) 3-cm-long reversed-phase column fully resolves uroporphyrin, hepta-, hexa-, and pentacarboxylic acid porphyrins, and coproporphyrin. Instrument response is linearly related to concentration over the range 25 to 300 nmol/L. The method provides data essential for the differential diagnosis of porphyric states, including porphyria variegata and porphyria cutanea tarda. This relatively inexpensive method requires a run time of only 8 min per sample, making it particularly suitable for routine use in the clinical chemistry laboratory.

Chromatography, High Pressure Liquid↗
PubMed1986

Pattern of colony-stimulating activity in HL-60 cells after phorbol-ester-induced differentiation.

HL-60 cells secrete an autostimulatory activity (ASA) that appears to be required for their growth in vitro. The purpose of this study was to examine the pattern of colony-stimulating activity in conditioned media of HL-60 after induction of differentiation by the phorbol ester phorbol-12-myristate-13-acetate (PMA). PMA-induced differentiation to monocyte-macrophage cells was accompanied by persistence of ASA secretion and the appearance of new species of colony-stimulating activities similar in properties to human CSF I and CSF II. Thus the secretion of ASA by HL-60 appears to be a characteristic property of these cells that is maintained after terminal differentiation.

Cell Differentiation↗
PubMed1985

Oxidation state analysis of mercury: evidence of the formation of mercurous ion in the oxidation of mercury by peracetic acid.

Both elemental mercury and the mercurous ion give rise to a signal in Cold-Vapor Atomic Absorption Analysis under non-reducing conditions. Distinction between these species based on the greater solubility of the mercurous ion in water is possible, and the potential of this analytical distinction is illustrated with the finding that oxidation of mercury by peracetic acid involves the mercurous state.

Acetates↗
PubMed1984

Human myeloid leukemic cell (HL-60) autostimulator: relationship to colony-stimulating factor.

The human promyelocyte leukemic cell line HL-60 secretes a glycoprotein factor which stimulates HL-60 and myeloid cell growth and colony formation in vitro. Functional and biochemical studies indicate this autostimulatory activity (ASA) is distinct from colony-stimulating factor (CSF) activities reported previously. Human CSF I, CSF II, and HL-60 ASA stimulated HL-60 growth and colony formation. The ASA also demonstrated CSF activity for both granulocyte and macrophage colonies when assayed on normal mouse and human bone marrow cells. The ASA glycoprotein was partially purified 1200-fold to an apparent molecular weight of 25,000 on G-75 filtration and a pl of 4.9 after neuraminidase treatment. Serological cross-reactivity between human CSF I and HL-60 ASA was detectable by immune precipitation and neutralization of biological activity with rabbit anti-CSF I antibodies. The cross-reactive anti-CSF I antibodies also inhibited spontaneous HL-60 colony formation in vitro in the absence of exogenous CSF, ASA, or anti-HL-60 antibody activity. These results indicate that HL-60 ASA is an endogenous growth factor similar to CSF that may be required for HL-60 growth in vitro.

Animals↗
PubMed1983

Oxidation of mercury by catalase and peroxidase in homogeneous solution.

Experiments in homogeneous solution confirm previous findings that catalase is an effective oxidant for Hg0 leads to Hg2+. Peroxidase also effects the oxidation, and in both oxidations the co-substrate hydrogen peroxide is not essential for mercury oxidation, although the oxidation is enhanced by the presence of hydrogen peroxide.

Animals↗
PubMed1982

Linkage of the isoprenoid biosynthetic pathway with induction of DNA synthesis in mouse lymphocytes. Effects of compactin on mitogen-induced lymphocytes in serum-free medium.

Concanavalin A induction of DNA synthesis in mouse spleen lymphocytes cultured in serum-free medium was shown to be very sensitive to inhibition by compactin (ML-236B), a specific competitive inhibitor of hydroxymethylglutaryl-CoA reductase. As low as 0.1 microM compactin could give 98% inhibition of mitogen induction of a 5.10(6) cells/ml culture. This inhibition could be reversed completely by addition of exogenous mevalonate, but could not be reversed by either exogenous cholesterol or isopentenyladenine. Oxygenated sterol inhibition of mitogen-induced DNA synthesis could be reversed by cholesterol or by mevalonate, whereas cyclic AMP inhibition could not be reversed by either compound. These results suggest that endogenous cholesterol production is a necessary but not sufficient factor co-ordinated with mitogen-induced DNA synthesis, and that the presence of some additional product of mevalonate metabolism is involved also. Isopentenyladenine, though, did not have as significant effect of alleviating any of the above inhibitions. Since mevalonate could not relieve cyclic AMP inhibition, but could overcome compactin inhibition, cyclic AMP inhibition cannot be explained as due only to blockage of mevalonate production.

Animals↗
PubMedDate not supplied

Familial Wilms' tumor with neural elements: characterization by histology, immunohistochemistry, and genetic analysis.

Wilms' tumor (WT) is the most common renal malignancy of children. While most occur sporadically, a small percentage are familial or occur as part of a developmental syndrome. Classic WTs exhibit a triphasic histologic pattern composed of blastema, epithelium, and stroma. Occasionally, heterologous elements may also be observed. In this study we investigated a series of four WTs that occurred within a single familial aggregate and contained focal areas of neural differentiation. The tumors were evaluated histologically for the presence of neural elements and immunohistochemically for expression of neural-related markers. Genetic linkage analysis was performed on 3 of the 4 WTs. In addition to the classic triphasic histology, the WTs contained tumor rosettes (4/4), ganglion cells (2/4), foci of ganglioneuromatous differentiation (2/4), and anaplasia (1/4). Staining for chromogranin, S-100, synaptophysin, vimentin, and neuron-specific enolase was positive in all 4 tumors within the areas of neural differentiation whereas staining for CD99 (013) and glial fibrillary acidic protein was negative. Linkage analysis studies suggest that the familial predisposition gene segregating in this family is at 19q13.4. To our knowledge, this is the first reported series of WTs with neural differentiation that occurred within a single family aggregate. Genetic linkage analysis of this family is consistent with linkage to the FWT2 WT predisposition gene at 19q13.4. We propose that these tumors may represent a unique manifestation of tumor susceptibility in this family.

Biomarkers, Tumor↗
PubMedDate not supplied

Work-up and diagnosis of pediatric non-Hodgkin's lymphomas.

Non-Hodgkin's lymphomas (NHL) in children and adolescents represent about 10% of childhood cancers. Although the types of NHL commonly seen in this population are relatively limited to lymphoblastic lymphomas, Burkitt's and Burkitt-like lymphomas, and large cell lymphomas, correct diagnosis and classification are essential for optimal therapy. Careful handling of pathologic specimens, along with collection of proper materials for ancillary studies such as immunophenotyping, cytogenetics, or molecular studies, will aid the pathologist in reaching a correct diagnosis. Specific morphologic, immunophenotypic, and genetic features of the commonly seen types of pediatric NHL are described.

Adolescent↗
PubMedDate not supplied

Age-related bone loss in mice is associated with an increased osteoclast progenitor pool.

Age-associated osteopenia has been documented to occur in mice and, therefore, provides a model system whereby mechanisms of bone loss can be assessed in vivo and in vitro. One such mechanism, that could explain the increased resorptive activity seen in some forms of osteopenia, is an age-associated increase in the osteoclast precursor pool and osteoclastogenic formation. To test this hypothesis, we studied the bone marrow composition of aged (24 months) mice to determine if increased numbers of monocyte/macrophage/osteoclast precursor cells (MMOPC) were present when compared to young (4-6 months) animals. Our data show a moderate increase of 20-30% more hematopoietic cells obtained from the long bones of the aged animals. However, both liquid and semi-solid culture techniques demonstrate an approximately 2-3.5-fold increase in the numbers of plastic adherent macrophages or mononuclear colonies in bone marrow derived from the aged mice when stimulated by interleukin-3 (IL-3), granulocyte-macrophage colony stimulating factor (GM-CSF) or macrophage colony stimulating factor (GM-CSF), indicating a preferential increase in MMOPCs. In addition, cells derived from the aged mice show higher levels of cytokine stimulated incorporation of [3H]-thymidine and [3H]-leucine, with increased protein synthesis seen up to 7 days after cytokine stimulation, suggesting that these cells also have an enhanced sensitivity to cytokines.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMedDate not supplied

Elimination of the matrix effect in the cold-vapor atomic absorption analysis of mercury in human hair samples.

The percent recovery of mercury from human hair digest samples, using the peak height cold-vapor atomic adsorption method is 73.0% +/- 10.3%. This value and its reproducibility are raised to 102.2% +/- 6.3% by use of peak area measurements in place of peak height. The so-called matrix effect is thus eliminated, and its origin shown to be in the slower (but still quantitative) release of mercury from biological samples. Although greater reliability is obtained using peak area, this is gained at the cost of analysis time.

Hair↗