4-Aminobutyrate aminotransferase, reaction of P'P2-bis(5'-pyridoxal) diphosphate with lysyl residues connected with catalytic activity

4-Aminobutyrate aminotransferase is inactivated by preincubation with bispyridoxal-5-P (mixing molar ratio, 20:1) at pH 7.0. The reaction with bispyridoxal-5-P under pseudo-first order conditions proceeds at a slow rate (kobs = 0.03 min-1). The extent of chemical modification was determined by measuring the spectroscopic properties of P-pyridoxyl and P-pyridoxine chromophores formed after reduction of the enzyme reacted with P'P2-bis(5'-pyridoxal) diphosphate. Reduction with NaBH4 results in the incorporation of approximately 2.1 P-pyridoxyl residues/dimer. Thus, the blocking of 2 lysyl residues/dimer is needed for inactivation of the aminotransferase. The time course of inactivation is significantly affected by variations in the pH of the reaction mixtures. Plots of Kobs versus pH indicate the reaction of the bifunctional reagent with lysyl residues characterized by low pK values (pK = 7.3). The substrate alpha-ketoglutarate (10 mM) affords complete protection against inactivation, whereas pyridoxal-5-P failed to prevent the inactivation of the enzyme by bispyridoxal-5-P. It is postulated that binding of alpha-ketoglutarate to lysyl residues is the major factor contributing to stabilization of the catalytic site. Several lines of experimental evidence indicate that inactivation of the aminotransferase cannot be related to dissociation of the cofactor from the catalytic site. The bifunctional reagent bispyridoxal-5-P blocks lysyl residues other than those involved in the binding of the cofactor.

Correlation of histochemical and biochemical analyses of androgen binding in prostatic cancer: relation to therapeutic response

A histochemical technique for the detection of androgen binding in prostatic cancer was performed on specimens from 108 patients and compared with a biochemical method in a double blind study of 77. Statistical analyses showed a significant agreement between the two assay systems for the qualitative and quantitative presence or absence of specific androgen binding, as well as for the subcellular localization of binding in nucleus and/or cytoplasm. Although the number of cases studied was too small for statistical analysis, there appeared to be good correlation between histochemical androgen binding results and clinical response, or lack of response to hormonal manipulation in 20 patients with State C and Stage D carcinoma. No correlation was evident between androgen binding and tumor grade or clinicopathologic stage of disease of either histochemistry or biochemistry.

Gabaculine and m-carboxyphenyl-pyridoxamine 5-phosphate as probes of the catalytic binding sites of 4-aminobutyrate aminotransferase

A homogeneous 4-aminobutyrate aminotransferase isolated from pig brain exhibits a k(cat) of 9.6 s-1 and contains one mole of pyridoxal 5-phosphate/mole of dimer. THe reaction of the enzyme with gabaculine (5-amino-1,3-cyclohexadiene carboxylic acid) was studied by observing changes in the absorption spectrum of the bound cofactor and by monitoring loss of catalytic activity. The enzyme is completely inactivated by gabaculine, but the dialyzed inactive sample containing 0.5 mol of gabaculine/mol dimer is fully reconstituted by addition of pyridoxal 5-phosphate. Stopped-flow kinetic studied reveal that gabaculine reacts with the cofactor bound to the aminotransferase with a second-order rate constant of 2.5 X 10(3) M-1 s-1. Fluorometric titrations of the apoprotein with m-carboxyphenyl-pyridoxamine 5-phosphate show the binding of two moles of inhibitor/mole of enzyme. The binding process is reversible and the affinity of the apoprotein for the inhibitor is at least 10-fold higher than the affinity for the cofactor. It is postulated that the dimeric enzyme contains two potential active sites per dinner, but the binding site characterized by a weaker affinity constant for pyridoxal 5-phosphate becomes functional only after specific chemical modification of the molecule of cofactor tightly bound to the protein.

Ultrasonography and oral cholecystography: a comparison of their use in the diagnosis of gallbladder disease

The charts of all cholecystectomy patients at the White Memorial Medical Center, Los Angeles, from January 1977 to December 1979 were reviewed; of 374 patients, 76 had had both abdominal ultrasound scan and oral cholecystography performed preoperatively. Cholecystography accurately diagnosed gallbladder disease in 71 of these 76 patients, an accuracy rate of 93.4% with one false-positive and four false-negative results. Ultrasonography correctly predicted gallbladder disease in 66 of 76 patients, an accuracy rate of 86.8%, with one false-positive and nine false-negative results. On the basis of this study and others in the literature, ultrasound scanning is recommended as the initial screening diagnostic study for gallbladder disease. Oral cholecystography should follow in patients in whom ultrasonography fails to identify gallbladder calculi.

An improved histochemical method for detection of estrogen receptors in mammary cancer. Comparison with biochemical assay

Unselected, consecutive surgical specimens from 120 women with cancer of the breast were subjected to histochemical assay for the presence of estrogen receptor. A fluoresceinated bovine serum albumin--estradiol conjugate was used that linked estradiol at position 17 and contained 5 mol fluorescein and 4 mol estradiol per mole albumin. Simultaneous competitive binding studies with excess unlabeled estradiol, diethylstilbestrol, and the antiestrogen nitromifene citrate were regularly performed. Results were compared to those obtained by the dextran-coated charcoal receptor assay. Three specimens were necrotic, two others thawed, and two lacked sufficient protein for biochemical analysis. One specimen did not contain tumor, and 11 others showed a predominant nuclear staining pattern. Nuclear receptor was not assayed biochemically. Comparison of results in the remaining 101 cases showed agreement in 92%. The precedure is uncomplicated, economical, and could be performed and interpreted in any pathology laboratory.

Histochemistry of steroid receptors in breast cancer: an overview

Immunofluorescence and a new histochemical technique were employed to assay 226 breast cancer specimens for estrogen receptor. Results showed an overall correlation of 91 percent when compared to those of biochemical assays. The histochemical technique is rapid, easy to perform and reveals the same parameters as does immunofluorescence without the need for antiserum. Tumor cell receptor heterogeneity and location of receptor in cytoplasm or nucleus is readily defined by both methods. These histologic tests should prove to be useful in extending the availability of estrogen receptor analysis to all patients with breast cancer.

Histochemistry of steroid receptors in prostatic diseases

Tissue obtained from 55 men with prostatic disease was assayed for estrogen and androgen receptors by a newly developed histochemical technique. The material studied consisted of 45 specimens of benign nodular prostatic hyperplasia and 10 specimens of prostatic adenocarcinoma. The results obtained were compared to those of parallel biochemical assays in 17 cases and successfully correlated in 85 percent. The new procedure is rapid, inexpensive and accurate, allowing for the detection of receptor in cytoplasm and/or nucleus and evaluation of receptor heterogeneity. The histochemical method may offer an alternate to biochemical assay of prostatic tissue as contamination with steroid binding globulins does not appear to be a problem at this time.

Detection of androgen and estrogen receptors in human prostatic carcinoma and hyperplasia by fluorescence microscopy

The histochemical detection of androgen and estrogen receptors in human prostatic tissue was achieved employing fluorescein labeled conjugates of bovine serum albumin linked to testosterone and estradiol. Results were compared to those of dextran-coated charcoal and protamine sulfate assays and correlated in 85% of specimens. Early findings include a relatively uniform distribution of receptor in hyperplastic epithelium in contrast to marked tumor cell receptor heterogeneity in cancer. Location of receptor in nucleus and/or cytoplasm was readily determined.

Immunofluorescent detection of estrogen receptors in breast cancer. Comparison with dextran-coated charcoal and sucrose gradient assays

Biopsy specimens from 106 women with primary operable, recurrent or metastatic breast cancer were analyzed in a double blind study designed to compare the results of a new fluorescent antibody method for detection of estrogen receptors with estrogen receptors measured biochemically with dextran-coated charcoal and sucrose gradient assay techniques. Assay results correlated in 89.4% of tumors analyzed, and molecular receptor forms (8S and 4S) were accurately predicted in 94.7% of neoplasms studied. Divergent results most often occurred in specimens sparsely populated with malignant cells. The new technique permitted recognition of possible sources of false negative results such as necrosis, absence of tumor and, on occasion, estrogen bound in vivo. It was possible to analyze by the immunofluorescence method two specimens of insufficient size for biochemical assay.

Primate model for the evaluation of vaginal contraceptives

A good animal model that simulates the human subject has not been available for the evaluation of the in vivo effectiveness of vaginal contraceptives. After careful consideration. The stumptailed macaque (Macaca arctoides) was studied for its applicability since it has a reproductive tract similar to that of the woman, is easy to handle, does not require tranquilization or anesthesia when the contraceptive is deposited, and breeds and conceives readily under caged conditions. The reported observations show the usefulness of this animal. Both postcoital sperm motility studies and breeding experiments were performed with the use of Delfen vaginal cream and K-Y jelly. K-Y jelly had no effect on the motility of vaginal spermatozoa or on the conception rate of the primates. Although Delfen vaginal cream consistently immobilized all spermatozoa in the postcoital test, half of the animals became pregnant within an average of 3.7 breeding cycles. These results illustrate the discrepancy between spermicidal tests and fertility measurements, and it is recommended that primate-breeding experiments be performed before a spermicide is evaluated in women as a contraceptive.

Jejunal immunopathology in amyotrophic lateral sclerosis and multiple sclerosis. Identification of viral antigens by immunofluorescence

Jejunal mucosa from 7 patients with amyotrophic lateral sclerosis (A.L.S.), 20 newly reported patients with multiple sclerosis (M.S.), and 35 control patients without either disease was studied by immunofluorescence. An immune reaction was present in all A.L.S. specimens and consisted of altered ratios of immunoglobulin-labelled cells in the lamina propria, complement-labelled cells in the same location, and, in some, immunoglobulin and complement deposits in the epithelial basement membrane. Poliovirus antigen was detected in 4 cases, and in 1 of the these cases measles antigen was also present. A fifth specimen showed large amounts of herpesvirus antigen. In 2 cases studied at necropsy, both viral infection and immunological change was confined to the proximal jejunum. Measles antigen was identified in every case of M.S., and in biopsy specimens from 16 of the 20 M.S. patients immunological reactions similar to those seen in A.L.S. were present. With 2 exceptions, the controls did not show these changes in the jejunal mucosa. The exceptions were a patient with Friedreich's ataxia, who had an increase of IgG-labelled cells and some complement-bearing cells in the lamina propria, and a patient diagnosed as having non-tropical sprue, in whom large quantities of herpes antigen were seen.

Height and antisocial behavior in XY and XYY boys

The observed association of the XYY genotype with both (i) large height in childhood and (ii) institutionalization for antisocial behavior suggested that large size per se in childhood might tend to establish personality patterns leading to eventual incarceration for delinquency. To investigate this question, the height distributions of four groups of XY boys in institutions for nonpsychotic, nonretarded juvenile offenders were compared with the published standards as well as the predicted gaussian distributions calculated from the mean and variance of the age-adjusted heights of each group. In none of these groups was there evidence for an increased number of large individuals. But three XYY individuals in the same institutions all had heights greater than the 90th percentile of XY boys of the same race.