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Biomedical subjects

J A Roth

Publications and source records attributed to J A Roth.

At least 397 records · Page 22Linked to original sources
PubMed1987

Kinetic reaction mechanism for magnesium binding to membrane-bound and soluble catechol O-methyltransferase.

Catechol O-methyltransferase (COMT, EC 2.1.1.6) from human brain occurs in both a membrane-bound (MB-COMT) and a soluble form (SOL-COMT). While these enzymes appear to be distinct molecular entities, both catalyze the O-methylation of catecholamines through an ordered reaction mechanism in which S-adenosylmethionine (SAM) is the leading substrate [Rivett, A. J., & Roth, J. A. (1982) Biochemistry 21, 1740-1742; Jeffery, D. R., & Roth, J. A. (1985) J. Neurochem. 44, 881-885]. Both MB-COMT and SOL-COMT require the presence of divalent cations for catalytic activity. This series of experiments provides evidence indicating that magnesium ions bind to both MB-COMT and SOL-COMT in a rapid equilibrium sequence prior to the addition of SAM. An equation is presented that predicts the qualitative results obtained in all kinetic experiments carried out with either MB-COMT or SOL-COMT.

Brain↗
PubMed1987

Immunologic and virologic findings in a bull chronically infected with noncytopathic bovine viral diarrhea virus.

Depressed lymphocyte blastogenesis in response to mitogen stimulation, depressed iodination of protein by neutrophils, and enhanced ingestion of Staphylococcus aureus by neutrophils were detected in a bull with chronic bovine viral diarrhea (BVD). Before developing chronic BVD, the bull was vaccinated with a killed cytopathic BVD virus. Neutralizing antibodies specific for the vaccine virus were detected in serum specimens obtained from the bull immediately before death. A noncytopathic BVD virus was isolated from the spleen after death. The immunologic and virologic findings in this bull supported reported research findings on the pathogenetic mechanisms involved in chronic BVD and mucosal disease.

Animals↗
PubMed1987

Studies of the in vitro effect of methylmercury chloride on rat brain neurotransmitter enzymes.

The in vitro effect of methylmercury (MM) on the enzymatic activities of brain cell specific marker enzymes, choline acetyltransferase (CAT), glutamic acid decarboxylase (GAD), 2',3'-cyclic nucleotide phosphohydrolase (CNP), glutamine synthetase (GS) and enolase was examined. The results demonstrate that at 100 microM MM, GS activity was not affected whereas a small decrease in the activity of both GAD (20%) and enolase (10%) was observed. CNP and CAT activity appeared to be more sensitive toward MM with 100 microM MM producing inhibition of 50% and 30%, respectively. The addition of sulfhydryl protecting reagents such as DTT or sodium thioglycolate can restore the enzyme activities to normal control levels despite prior exposure of the enzymes to MM.

Animals↗
PubMed1987

Relationship of glucocorticoid suppression of arachidonic acid metabolism to alteration of neutrophil function.

The role of arachidonic acid metabolism in glucocorticoid-induced suppression of neutrophil function was investigated. In vivo treatment of cattle with dexamethasone decreased the production of lipoxygenase products of arachidonic acid metabolism (leukotriene B4 [LTB4] and H-5-hydroxy-6,8,11,14-eicosatetraenoic acid [5-HETE]) in neutrophils. We previously reported that in vivo dexamethasone treatment resulted in alteration of in vitro neutrophil oxidative metabolism, iodination, antibody-dependent cell-mediated cytotoxicity (ADCC), and random migration. To determine if the decrease in production of LTB4 and 5-HETE were responsible for the changes in neutrophil function, neutrophils were treated in vitro with inhibitors of the lipoxygenase enzyme (BW755c and nordihydroguaiaretic acid), and their function was evaluated. A decrease in neutrophil oxidative metabolism and iodination was observed, but there was no effect on neutrophil random migration or ADCC. The results suggest that in vivo treatment with glucocorticoids inhibit neutrophil oxidative metabolism and iodination by decreasing the formation of lipoxygenase products of arachidonic acid metabolism but alter neutrophil random migration and ADCC by a mechanism independent of arachidonic acid metabolism.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1987

Heterogeneous expression of a murine B16 melanoma-associated antigen correlates with cell cycle.

A murine monoclonal antibody (MM2-3C6) that reacts with a B16 murine melanoma-associated membrane antigen was used to study the relationship of antigen expression to the cell cycle. Dual-parameter flow cytometric measurements of membrane antigen and DNA revealed that antigen-positive cells were present throughout the cell cycle. Peak antigenic expression was noted during the late log phase of the cell growth curve with negligible antigen-negative population. The emergence of a distinct antigen-negative population (30%-40%) was noted in the late stationary phase. Cell cycle analysis indicated that the negative subpopulation was restricted to the G0/G1 phase, thus, demonstrating antigenic heterogeneity within the tumor cell population. Cell sorting was performed to analyze the origin of such heterogeneity. Following two sequential sortings, the antigen-negative cells became antigenic upon reculture. Again, at the late stationary phase, a distinct antigen-negative population (30%-40%) emerged. The sorted antigen-positive cells showed flow cytometric profiles identical to the sorted antigen-negative population upon reculture. Therefore, in this murine model, it appears that antigen expression is cell cycle dependent and such expression seems to be associated with proliferation.

Animals↗
PubMed1987

Possible association of thymus dysfunction with fading syndromes in puppies and kittens.

"Wasting" or "fading" syndromes are common causes of puppy and kitten mortality. Numerous infectious and toxic, metabolic, or nutritional factors could potentially be responsible for wasting and death in young animals. Evidence has been presented that infectious canine hepatitis virus infection, beta-hemolytic streptococcus infection, and feline infectious peritonitis virus infection are responsible for a significant number of deaths due to wasting syndrome. However, many cases of wasting syndrome cannot be attributed to infectious agents or other specific etiologies. The thymus gland warrants special attention when one is evaluating an animal with a wasting syndrome because it is known that, in some species, neonatal thymectomy results in wasting and death. Unfortunately, most reports describing fading syndromes in puppies and kittens do not mention the gross or histologic appearance of the thymus gland at postmortem examination. When examining the thymus gland, one must keep in mind that the thymus may be hypoplastic owing to a congenital or genetic defect in its structure and function or it may be atrophic secondary to whatever is causing the fading syndrome. If a thorough history, clinical examination, and/or postmortem examination do not reveal a cause for the fading syndrome, then defective thymus function should be considered as a possible causative or contributing factor to the fading syndrome. In these cases, therapy designed to replace or improve the defective thymus function should be considered. At least one form of wasting syndrome in puppies (immunodeficient dwarfism) has been found to respond to short-term therapy with a thymus hormone (thymosin fraction 5) or with bovine growth hormone (which is thymotropic) in limited clinical trials. It is possible that other forms of wasting or fading syndromes would also respond to therapy with thymus hormone or growth hormone. Certain thymus hormones (thymopoietin pentapeptide, thymosin alpha 1, facteur thymique serique, and rabbit thymus acetone powder) and bovine growth hormone are commercially available. Before initiating therapy, one should consider that if the cause of the wasting syndrome is genetic, then successful treatment may perpetuate a genetic defect. More research (both basic and clinical) is needed to determine the role of thymus gland dysfunction in fading syndromes of puppies and kittens and if therapy with one or several of the thymus hormones or with growth hormone could reverse the symptoms of wasting.

Animals↗
PubMed1987

Inhibition of M and P phenol sulfotransferase by analogues of 3'-phosphoadenosine-5'-phosphosulfate.

Structural analogues of the sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (3',5'-PAPS) were examined for their ability to inhibit dopamine and phenol sulfation by the M and P forms of phenol sulfotransferase (PST), respectively. The Ki values for each of the adenosine derivatives were calculated from the rate equation for PST. For both M and P PST, the naturally occurring product 3'-phosphoadenosine-5'-phosphate, (3',5'-PAP), was shown to be the most effective inhibitor. The weakest inhibitors of the two sulfotransferases were 5'-adenosine phosphosulfate and the three AMP derivatives, which were less than 1,000 times as effective as 3',5'-PAP. 5'-ATP, 2',5'-PAPS, 2',5'-PAP, and 5'-ADP were similar in their inhibition of M and P PST and were all approximately 100 times less effective than the natural end product. These data reveal that there is a rigid structural requirement for binding of the ribose portion of adenosine to both M and P PST that involves the groups on both the 3' and 5' positions. The effectiveness of binding to the two enzymes may depend on both steric factors as well as the distribution of negative charges on the ribose ring.

Adenine Nucleotides↗
PubMed1987

Further evidence that the pigment in the Dubin-Johnson syndrome is not melanin.

The pigment in the Dubin-Johnson syndrome (DJS) is shown unequivocally not to be a typical melanin or closely related polymer. In electron spin resonance (ESR) studies of DJS pigment from a hepatoma, it is shown that, unlike true melanins, the pigment associated with the DJS syndrome has no free radical in the absence of light. Exposure to even low levels of visible light over a broad frequency range induces a free radical in the DJS pigment. Previous studies did not appreciate the sensitivity to light of this pigment and therefore erroneously concluded that the DJS pigment had a permanent free radical. The light induced ESR signal in DJS tissue has spectroscopic properties that differ significantly from any known melanins. The pigment is not extracted by lipophilic solvents and is centrifuged down at 50,000g, but not at 5,000g.

Carcinoma, Hepatocellular↗
PubMed1987

Effects of growth hormone on the adult canine thymus.

The ability of bovine growth hormone therapy to stimulate regeneration of age involuted thymus glands in adult dogs was evaluated. The thymuses of growth hormone treated dogs regenerated, resembling thymic tissue of young dogs. Some of the thymuses of bovine serum albumin treated control dogs also regenerated, but only 2 of 5 control dogs had marked regeneration. White blood cell counts in peripheral blood were not different between groups. Serum thymosin alpha 1 concentrations were not different between groups, but decreased in each group during the treatment period.

Age Factors↗
PubMed1987

The role of resection in the treatment of pulmonary metastases from Ewing's sarcoma.

We have investigated the role of resection in the treatment of patients with isolated pulmonary metastases from Ewing's sarcoma. In a retrospective review, 19 patients with the diagnosis of Ewing's sarcoma treated at the National Cancer Institute from 1965 to 1985 who underwent chest exploration for resection of pulmonary nodules were evaluated. Ten patients (53%) were made disease free by resection of pulmonary metastases, six patients (32%) were found to have unresectable disease, and three patients (16%) were found to have benign pulmonary disease. The actuarial 5 year survival rate of the 10 patients successfully made disease free by resection was 15%, and the median survival of this group was 28 months. In contrast, the median survival of the six patients not made disease free was 12 months, and no patient with residual disease was alive 22 months after thoracotomy (p2 = 0.0047). There were no postoperative deaths and only three minor postoperative complications for 25 operative procedures. Various prognostic variables were analyzed to determine their influence on postmetastasectomy survival. There was no difference in postmetastasectomy survival between patients who underwent resection of synchronous versus metachronous pulmonary metastases (p2 = 0.90). Patients who underwent resection of fewer than four malignant nodules had a significantly longer postmetastasectomy disease-free survival (p2 = 0.0019) and overall survival (p2 = 0.06) than those undergoing resection of four or more nodules. Patients who underwent resection of metastases that developed during chemotherapy had a significantly shorter postmetastasectomy survival that those who underwent resection of metastases that developed after chemotherapy (p2 = 0.0295). Our data show that selected patients with Ewing's sarcoma metastatic to the lungs may benefit from an aggressive surgical approach. Also, a significant proportion of these patients will have benign pulmonary disease and can thus avoid additional intensive systemic therapy.

Adolescent↗
PubMed1987

Growth hormone treatment stimulates thymulin production in aged dogs.

Diminished thymic morphology and function and a decreased provocative growth hormone (GH) response are characteristic of normal ageing. We have previously demonstrated that bovine growth hormone (bGH) treatment of adult dogs tends to result in a rejuvenation of thymic morphology. The purpose of this study was twofold: (1) to determine concentrations of thymulin (a thymic hormone) in plasma from dogs of various ages, and (2) to evaluate the effect of bGH administration on plasma thymulin concentration and thymus morphology in 'middle-aged' and 'old-aged' dogs. 'Young' (4 months), 'middle-aged' (33-55 months) and 'old-aged' (63-83 months) female beagles served as subjects for this study. Middle- and old-aged dogs were injected with either bGH or bovine serum albumin (control) for 1 month. Thymulin concentration in plasma was determined by the rosette-inhibition bioassay. An age-associated decline in the plasma concentration of thymulin was detected. Plasma thymulin concentration increased in every bGH-treated dog. In middle-aged but not old-aged dogs, bGH treatment resulted in rejuvenation of thymic morphological features as determined by stereological and histomorphological procedures. The results suggest that exogenous GH may be useful for restoration of some immune functions in aged individuals.

Aging↗
PubMed1987

Chronic active hepatitis and hepatic failure in the setting of idiopathic hemochromatosis.

We report a case of idiopathic hemochromatosis presenting clinically, biochemically, and histopathologically with features of chronic active hepatitis. Liver biopsy demonstrated excessive iron deposition as well as a striking inflammatory process. Progressive deterioration of hepatic function led to death despite return of iron levels to values seen in phlebotomy-treated patients with idiopathic hemochromatosis. This case suggests that patients with idiopathic hemochromatosis are not immune to other liver disorders and demonstrates the value of serum tissue iron studies in patients with liver disease of uncertain etiology.

Hemochromatosis↗
PubMed1986

Human oncogene-transfected tumor cells display differential susceptibility to lysis by lymphokine-activated killer cells (LAK) and natural killer cells.

NIH 3T3 tertiary transfectants containing the N-ras or c-Ha-ras oncogenes derived from human tumors were tested for susceptibility to lymphokine-activated killer (LAK) cell and natural killer (NK) cell lysis. N-ras tertiary transfectants contained a human acute lymphocytic leukemia-derived N-ras oncogene. C-Ha-ras transfectants contained either the position 61-activated form of the oncogene (45.342, 45.322, and 45.3B2) or the position 12-activated form (144-162). In 4 hr 51Cr release assays, seven of seven in vivo grown human oncogene transfected NIH 3T3 fibroblasts were lysed by murine LAK effectors, whereas six of seven were lysed by human LAK effectors. There was no difference in susceptibility to lysis between cells transfected with the N-ras oncogene, the position 61 activated c-Ha-ras oncogene, or the position 12 activated c-Ha-ras oncogene. Cultured NIH 3T3 fibroblasts, as well as in vitro and in vivo grown NIH 3T3 tertiary transfectants were resistant to lysis by murine NK effectors and were relatively resistant (4/6 were not lysed) to lysis by human NK effectors. We conclude that human oncogene-transfected tumors are susceptible to lysis by both murine and human LAK cells while being relatively resistant to lysis by murine and human NK cells. Different oncogenes or the same oncogene activated by different point mutations do not specifically determine susceptibility to lysis by LAK or NK. Also the presence of an activated oncogene does not appear to be sufficient for inducing susceptibility to these cytotoxic lymphocyte populations.

Adenocarcinoma↗
PubMed1986

Monoclonal antibody 45-2D9 recognizes a cell surface glycoprotein on a human c-Ha-ras transformed cell line (45-342) and a shared epitope on human tumors.

A monoclonal antibody (45-2D9) produced after immunization of BALB/c mice with the c-Ha-ras NIH 3T3 tertiary transfectant (45-342) recognized a determinant expressed by the primary, three of three secondary, and one of three tertiary transfectants, but not by NIH 3T3 cells. The determinant was present on the cell surface and was distinct from murine leukemia virus gp70 by absorption studies. Biosynthetic labeling and immunoprecipitation studies with [35S]methionine and [3H]glucosamine demonstrated that 45-2D9 recognizes a 74,000 Mr glycoprotein with minor bands of 90,000 and 180,000 Mr on SDS-PAGE. Pulse chase studies demonstrated a 68,000 Mr precursor molecule that incorporated only [35S]methionine. The distribution of the epitope recognized by 45-2D9 was assessed by immunoperoxidase staining. The antigen was not detected on 10 primary and metastatic murine tumors or 11 transformed murine cell lines. However, a variety of surgically excised human tumors demonstrated intense staining, whereas staining of normal tissues was minimal or not detectable. Thus a human oncogene-transfected cell can express a new cell surface determinant apparently unrelated to the oncogene product, which is also selectively expressed by human tumors.

Animals↗