PubMed Health⌕ Search

Biomedical subjects

E Allen

Publications and source records attributed to E Allen.

At least 19 recordsLinked to original sources
PubMed1992

Application of an organic solvent extraction to the determination of catechol-O-methyltransferase activity by high-performance liquid chromatography in human mononuclear cells.

We report here a method for measuring mononuclear cell catechol-O-methyltransferase (COMT) activity which is ideally adapted to clinical studies. The method measures the O-methylation of dopamine to 3-methoxytyramine and 4-methoxy-3-hydroxyphenethylamine. Whole mononuclear cell sonicate is incubated with saturating concentrations of dopamine, S-adenosyl-L-methionine and magnesium chloride in sodium-potassium phosphate buffer at pH 7.3. An organic solvent extraction using ethyl acetate is then used for product separation, followed by high-performance liquid chromatography with electrochemical detection for product separation and quantification. This method allows both O-methylated products, 3-methoxytyramine and 4-methoxy-3-hydroxyphenethylamine, to be isolated and quantified separately. The apparent Michaelis constants for dopamine and S-adenosyl-L-methionine using this method are similar to values reported previously (0.51 and 14 microM, respectively). The optimal concentration of magnesium chloride is eight to ten times higher than previously reported. No endogenous inhibitors were apparent using this assay. The within-day coefficient of variation using this method is 7% when measuring 3-methoxytyramine and 5% when measuring 4-methoxy-3-hydroxyphenethylamine. The between-day coefficient of variation is 11%. Mononuclear cell COMT activity can be detected using protein concentrations as low as 0.75 mg/ml, corresponding to 2-3 ml of whole blood. The small amount of blood required per sample allows multiple sample analysis from a single patient, including infants.

Adult↗
PubMed1991

Establishment and characterization of a human carcinoid in nude mice and effect of various agents on tumor growth.

The authors have established a long-term tissue culture cell line (BON) derived from a metastatic human carcinoid tumor of the pancreas. The cells have been in continuous passage for 46 months. Tissue culture cells produce tumors in a dose-dependent fashion after SC inoculation of cell suspensions in athymic nude mice. BON tumors, grown in nude mice, are histologically identical to the original tumor; they possess gastrin and somatostatin receptors, synthesize serotonin and chromogranin A, and have a doubling time of approximately 13 days. The antiproliferative effects of the long-acting somatostatin analogue, SMS 201-995 (300 micrograms/kg, t.i.d.), and 2% alpha-difluoromethylornithine on BON xenografts in nude mice were examined. Tumor size was significantly decreased by day 14 of treatment with either agent and at all points of analysis thereafter until the animals were killed (day 33). In addition, tumor weight, DNA, RNA, and protein contents were significantly decreased in treated mice compared with controls. Establishment of this human carcinoid xenograft line, BON, provides an excellent model to study further the biological behavior of carcinoid tumors and the in vivo effect of chemotherapeutic agents on tumor growth.

Animals↗
PubMed1990

Serum levels of pregnancy-associated endometrial alpha 2-globulin (alpha 2-PEG), a glycosylated beta-lactoglobulin homologue, in successful and unsuccessful assisted conception.

Pregnancy-associated endometrial alpha 2-globulin (alpha 2-PEG) is the major secretory protein of the endometrium in the late luteal phase. Serum levels were measured during the implantation period in successful and unsuccessful cycles of assisted conception. The effects of two different treatment regimens were also compared. All patients who underwent ovulation induction therapy showed an endometrial response as measured by a rise in serum levels of alpha 2-PEG. This rise was the same regardless of either implantation or the method of ovulation induction used. Higher levels were seen at oocyte recovery in those cycles treated with clomiphene citrate and may reflect a disordered endometrial response involving a direct effect of the drug on the endometrium. This may explain the difference in success rates in assisted conception when an alternative treatment initially involving down-regulation of endogenous gonadotrophin activity and subsequent administration of gonadotrophins is used. The rise in serum levels seen in pregnancy did not differ statistically according to whether the pregnancy progressed normally or subsequently aborted. Considerably reduced alpha 2-PEG production by the endometrium was identified in one patient who subsequently aborted. The measurement of serum levels of alpha 2-PEG during the implantation phase is unlikely to provide a clinical tool either for early detection of pregnancy or as a prognostic factor of successful implantation.

Abortion, Spontaneous↗
PubMed1990

Phenotype, ultrastructure, and function of CD1+DR+ epidermal cells that express CD36 (OKM5) in cutaneous T-cell lymphoma.

This study investigated the phenotype and function of different antigen-presenting cells (APC) present within the epidermis of patients with cutaneous T-cell lymphoma (CTCL). Involved epidermis of CTCL compared with uninvolved was found to contain increased numbers of CD1+DR+ APC. This population was heterogeneous and comprised both leucocytes of a novel CD1+DR+CD36 (OKM5)+ phenotype and CD1+DR+CD36- indeterminate/Langerhans cells. The CD1+DR+CD36+ leucocytes did not express TcR-1, CD5, CD15, or CD22, and only a minor population expressed CD11, demonstrating that they were neither T nor B cells, and did not belong to the major CD11+ (OKM1+) blood monocyte population. Electron microscopy of purified CD36+ lesional epidermal cells (EC) demonstrated that they lacked Birbeck granules found on CD1(+)-selected Langerhans cells, and most cells exhibited features of indeterminate cells or macrophages. The capacity of EC from involved epidermis to present alloantigens was found to be increased relative to uninvolved epidermis in all patients tested, and this capacity was critically dependent upon the presence of CD45+DR+ bone marrow-derived cells but not on the presence of CD45-DR+ keratinocytes. Positive selection using MoAb against CD1 and CD36 demonstrated that both cell populations exhibited the capacity to stimulate T cells. The results indicate that a novel antigen-presenting cell population with a unique phenotype is present within involved skin of patients with mycosis fungoides. These cells express CD36 in addition to CD1 and have an ultrastructural appearance consistent with a dendritic antigen-presenting cell derivation.

Antibodies, Monoclonal↗
PubMed1990

Effect of total jejunoileal denervation on fat-stimulated release of peptide YY and cholecystokinin.

We have investigated the effect of total denervation of the jejunoileum (JDNv) on stimulated release of peptide YY (PYY) and cholecystokinin-33/39 in five dogs prepared with chronic gastric and duodenal cannulas. JDNv was performed by stripping the adventitia from the superior mesenteric artery and vein, transecting the small bowel mesentery, and division (with reanastomosis) of the small bowel at the ligament of Treitz and ileocecal junctio. Introduodenal corn oil (3 ml/kg/hr) was given before JDNv and 1 and 2 months after JDNv. Intravenous bombesin (400 pmol/kg/hr) was given (on nonconsecutive days) before JDNv and 1 month after JDNv. Plasma PYY and cholecystokinin levels were measured by specific radioimmunoassay. Release of PYY was enhanced after JDNv. The integrated release of PYY (ng.[0 to 60 min]/ml) after intraduodenal corn oil was as follows: before JDNv, 4.1 +/- 1.2; 1 month after JDNv, 16.0 +/- 2.7; and 2 months after JDNv, 10.3 +/- 2.2. Similar results were noted with intravenous bombesin (3.7 +/- 0.9 [before JDNv] vs 12.0 +/- 0.7 [1 month after JDNv]). Corn oil-stimulated release of cholecystokinin was abolished after JDNv (before JDNv 2.2 +/- 1.1; 1 month after JDNv, 0.6 +/- 0.3; and 2 months after JDNv, 0.4 +/- 0.6). Basal plasma levels of PYY and cholecystokinin were not affected by JDNv. We conclude that JDNv enhances PYY and abolished cholecystokinin release, which provides evidence for different mechanisms of neural control.

Animals↗
PubMed1989

Evaluation of a serologic marker, CA19-9, in the diagnosis of pancreatic cancer.

STUDY OBJECTIVE: To determine the utility of the serologic marker CA19-9 in the diagnosis of pancreatic cancer in patients suspected of having a pancreatic disorder. DESIGN: Blinded study of frozen pedigreed serum samples collected at time of diagnostic evaluation with follow-up review at a mean of 8 years. SETTING: A general university teaching hospital serving both primary and referral patient populations. MEASUREMENTS AND MAIN RESULTS: Sera collected prospectively from 1978 to 1980 from 261 patients undergoing imaging studies of the pancreas (ultrasound, computed tomography, endoscopic retrograde cholangiopancreatography) for a variety of symptoms were assayed for CA19-9 levels, and the results were compared with earlier determinations of other potential markers for pancreatic cancer. In 54 patients ultimately shown to have pancreatic cancer, the CA19-9 assay showed a sensitivity of 70% with a median value of 349 u/mL (normal less than 70 u/mL) and range, 7.3 to 2,859,964 u/mL, whereas specificity of the marker in this population was 87%. The positive predictive value was 59%, and the negative predictive value was 92%. Results of CA19-9 testing in the small group of patients with definitive staging information showed no difference in sensitivity between patients with local/regional disease (n = 6) and those with distant metastases (n = 14), 50% compared with 71% (P = 0.613). CONCLUSION: CA19-9 was found to be a more sensitive and specific marker of pancreatic cancer than other serologic markers and should be a useful test in the patient with suspected pancreatic disease.

Adenocarcinoma↗
PubMed1989

Craniopagus parasiticus. Everard Home's Two-Headed Boy of Bengal and some other cases.

Craniopagus parasiticus, or épicome, is a rare teratological type, of which only six cases have been recorded in the medical literature. It differs from craniopagus conjoined twins in that the body and limbs of the parasitic twin are underdeveloped, leaving in some cases only a parasitic head, inserted on the crown of the autositic twin. The first case of this malformation was Everard Home's famous Twin-Headed Boy of Bengal, whose skull is preserved at the Hunterian Museum. In this historical review, Home's case is presented in some detail, and the later cases are used to explain further some of its particulars.

Abnormalities, Severe Teratoid↗
PubMed1989

Thyrotropin (TSH)-releasing hormone-stimulated TSH release and TSH concentration in the guinea pig pituitary, as determined by a heterologous radioimmunoassay.

Little is known regarding how the guinea pig (GP) compares with the rat in terms of TSH economy. To develop a heterologous RIA for GP TSH, rabbits were injected with GP TSH. In one rabbit (anti-gpTSH-8), antibodies that bound 125I-labeled bovine (b) TSH and rat (r) TSH but not 125I-labeled bLH or rPRL were generated. The binding of anti-gpTSH-8 to [125I]bTSH was inhibited in a parallel manner by bTSH over a range of 0.047-5.42 ng, rTSH over a range of 0.24-25 ng, and dilutions of GP pituitary extracts. This system, with bTSH as the standard, was employed as the basis for a heterologous TSH RIA (GP TSH RIA). The cross-reactions of rTSH and bLH in the GP TSH RIA were 45% and 7%, respectively. Rat and bovine FSH, GH, and PRL had little or no cross-reaction. GP pituitaries were incubated in vitro and dosed with LHRH and TRH. The GP TSH RIA detected an 11-fold increase in TSH in the medium in response to TRH and no change in immunoreactivity in response to LHRH. In contrast, a RIA for bLH detected a 25-fold increase in LH in the medium in response to LHRH and no increase in response to TRH. The TSH content in GP pituitaries was significantly lower than that in the rat (GP, 16.8 +/- 1.6 ng/mg; rat, 80.3 +/- 6.2 ng/mg; P less than 0.05) as were serum TSH concentrations (GP, 0.8 +/- 0.4 ng/ml; rat, 4.5 +/- 1.1 ng/ml; P less than 0.05). Thyroid hormone administration (T4 Rx) in both GP and rat produced a significant reduction in pituitary TSH content (GP control, 4.8 +/- 0.4 ng/mg; T4 Rx, 2.1 ng/mg; P less than 0.05; rat control, 52.4 +/- 4.0 ng/mg; T4 Rx, 20.5 +/- 1.6 ng/mg; P less than 0.05) and TSH release (GP control, 9.4 +/- 2.3 ng/ml; T4 Rx, 4.3 +/- 1.5 ng/ml; P less than 0.05; rat control, 357 +/- 81 ng/ml; T4 Rx, 133 +/- 27 ng/ml; P less than 0.05) from incubated hemipituitaries. Thyroidectomy in the rat was associated with a decrease in pituitary TSH content, but no change in pituitary content was found in thyroidectomized GPs. These studies demonstrate the feasibility of estimating GP TSH with a heterologous RIA that employs polyvalent antiserum against GP TSH as the first antibody and bTSH as the tracer and standard.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Cerebral arteriovenous oxygen difference as an estimate of cerebral blood flow in comatose patients.

The hypothesis that cerebral arteriovenous difference of oxygen content (AVDO2) can be used to predict cerebral blood flow (CBF) was tested in patients who were comatose due to head injury, subarachnoid hemorrhage, or cerebrovascular disease. In 51 patients CBF was measured daily for 3 to 5 days, and in 49 patients CBF was measured every 8 hours for 5 to 10 days after injury. In the latter group of patients, when a low CBF (less than or equal to 0.2 ml/gm/min) or an increased level of cerebral lactate production (CMRL) (less than or equal to -0.06 mumol/gm/min) was encountered, therapy was instituted to increase CBF, and measurements of CBF, AVDO2, and arteriovenous difference of lactate content (AVDL) were repeated. When data from all patients were analyzed, including those with cerebral ischemia and those without, AVDO2 had only a modest correlation with CBF (r = -0.24 in 578 measurements, p less than 0.01). When patients with ischemia, indicated by an increased CMRL, were excluded from the analysis, CBF and AVDO2 had a much improved correlation (r = -0.74 in 313 measurements, p less than 0.01). Most patients with a very low CBF would have been misclassified as having a normal or increased CBF based on the AVDO2 alone. However, when measurements of AVDO2 were supplemented with AVDL, four distinct CBF patterns could be distinguished. Patients with an ischemia/infarction pattern typically had a lactate-oxygen index (LOI = -AVDL/AVDO2) of 0.08 or greater and a variable AVDO2. The three nonischemic CBF patterns had an LOI of less than 0.08, and could be classified according to the AVDO2. Patients with a normal CBF (mean 0.42 +/- 0.12 ml/gm/min) had an AVDO2 between 1.3 and 3.0 mumol/ml. A CBF pattern of hyperemia (mean 0.53 +/- 0.18 ml/gm/min) was characterized by an AVDO2 of less than 1.3 mumol/ml. A compensated hypoperfusion CBF pattern (mean 0.23 +/- 0.07 ml/gm/min) was identified by an AVDO2 of more than 3.0 mumol/min. These studies suggest that reliable estimates of CBF may be made from AVDO2 and AVDL measurements, which can be easily obtained in the intensive care unit.

Arteries↗
PubMed1988

The human X-linked steroid sulfatase gene and a Y-encoded pseudogene: evidence for an inversion of the Y chromosome during primate evolution.

The mammalian X and Y chromosomes are thought to have evolved from a common, nearly homologous chromosome pair. Although there is little sequence similarity between the mouse or the human X and Y, there are several regions in which moderate to extensive sequence homologies have been found, including, but not limited to, the so-called pseudoautosomal segment, in which X-Y pairing and recombination take place. The steroid sulfatase gene is in the pseudoautosomal region of the mouse, but not in man. We have cloned and characterized the human STS X-encoded locus and a pseudogene that is present on the long arm of the Y chromosome. Our data in humans and other primates suggest that there has been a pericentric inversion of the Y chromosome during primate evolution that has disrupted the former pseudoautosomal arrangement of these genes. These results provide additional insight into the evolution of the sex chromosomes and into the nature of this interesting portion of the human genome.

Animals↗
PubMed1987

Cloning and expression of steroid sulfatase cDNA and the frequent occurrence of deletions in STS deficiency: implications for X-Y interchange.

Human STS is a microsomal enzyme important in steroid metabolism. The gene encoding STS is pseudoautosomal in the mouse but not in humans, and escapes X inactivation in both species. We have prepared monoclonal and polyclonal antibodies to the protein which has been purified and from which partial amino acid sequence data have been obtained. cDNA clones containing the entire coding sequence were isolated, sequenced, and expressed in heterologous cells. Variable length transcripts have been shown to be present and due to usage of alternative poly(A) addition sites. The functional gene maps to Xp22.3-Xpter and there is a pseudogene on Yq suggesting a recent pericentric inversion. Absence of STS enzymatic activity occurs frequently in human populations and produces a visible phenotype of scaly skin or ichthyosis. Ten patients with inherited STS deficiency were studied and eight had complete gene deletions. The possibility that STS deficiency results from aberrant X-Y interchange is discussed.

Amino Acid Sequence↗
PubMed1987

Monoclonal antibodies against the 1,4-dihydropyridine receptor associated with voltage-sensitive Ca2+ channels detect similar polypeptides from a variety of tissues and species.

Four monoclonal antibodies have been raised against voltage-sensitive Ca2+ channel dihydropyridine receptors from rabbit skeletal muscle. When tested by immunoblot assay of denatured transverse tubule membranes in reducing polyacrylamide gels, each recognised a single polypeptide of Mr approximately 140,000 that co-migrated with the large glycoprotein subunit of the purified receptor. In blots of nonreducing gels, a larger protein of Mr approximately 170,000 was seen and three of the antibodies recognised additional components at Mr approximately 310,000 and approximately 330,000. Crossreactive material of similar molecular mass was also seen in rabbit heart and brain, and in the skeletal muscle of other species.

Animals↗
PubMed1986

Very short patch mismatch repair in phage lambda: repair sites and length of repair tracts.

Five amber mutations in the repressor (cI) gene of bacteriophage lambda recombine anomalously with nearby cI mutations. When any of these markers is used in four-factor crosses, cI+ recombinants that are expected to require three cross-overs occur at high frequencies. These recombinants are attributable to very-short-patch (VSP) repair of specific mismatches in DNA heteroduplexes formed during recombination between the markers flanking cI. The sites of the repair-prone mutations and the lengths of repair tracts have now been determined. Amber mutations subject to VSP repair are C to T transitions in 5'CCATGG, the sequence methylated by the product of gene dcm, and also in the related 5'CAGG or 5'CCAG sequences. Ambers arising in CAG sequences found in other contexts, or in codons other than CAG, were not subject to VSP repair. Repair tracts rarely, if ever, exceed ten nucleotides in length, and can be as short as two nucleotides. A repair-prone mutation does not stimulate recombination between flanking cI markers.

Bacteriophage lambda↗
PubMed1985

Chemical and histochemical studies of normal and diseased human gastrointestinal tract. V. A differential diagnostic method for the histochemical classification of glycoproteins.

A differential diagnostic scheme is described for the division of colonic epithelial glycoproteins into eleven histochemically distinct classes. The scheme depends upon the use of seven histochemical techniques which, collectively, permit the differential staining of O-sulphate ester, sialic acid and its side chain O-acyl variants and vicinal diols located on carbohydrate residues other than sialic acids. Elements of the scheme also provide a general approach to the classification of epithelial glycoproteins in anatomic sites other than the colon. Application of the scheme permitted the classification of the epithelial glycoproteins in the mucosa 0.5-5.0 cm from human colonic tumours and provided direct confirmation of previous observations that changes from normal in the relative proportions of either side chain O-acylated sialic acids or sialic acids and O-sulphate esters can occur independently of one another.

Colonic Neoplasms↗
PubMed1985

Results of dipstick tests, visual inspection, microscopic examination of urine sediment, and microbiological cultures of urine compared for simplifying urinalysis.

Using microscopic sediment examination, reagent dipsticks, visual appearance, and microbiological culture, we studied 196 urine specimens collected under sterile conditions. We conclude that the sensitivities and specificities noted in the comparison of dipstick urinalysis with urine microscopy justify eliminating many microscopic examinations if a procedural flowchart is used. All 33 (16.8%) of the uncontaminated urine specimens showing substantial potential pathogen content on culture had either a turbid appearance or positive results for one or more dipstick tests. A positive dipstick test result for nitrite most consistently indicated that the urine should be cultured.

Bacteriuria↗