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J Pitha

Publications and source records attributed to J Pitha.

At least 109 records · Page 6Linked to original sources
PubMed1982

Mapping of mammalian beta-adrenoreceptors by use of macromolecular alprenolol derivatives. A comparison with amphibian erythrocyte receptors.

THe interaction of macromolecular alprenolol derivatives with beta-adrenoreceptors of rat heart, lung, and erythrocytes and frog erythrocytes has been studied. Macromolecular derivatives were prepared by covalently coupling alprenolol to dextrans containing a homologous series of spacer arms of various lengths. The affinity of these macromolecules for frog erythrocyte membranes increased with increasing length of spacer arm. In contrast, the affinity of these macromolecules for all mammalian membrane preparations was weak and insensitive to the length of the spacer arm. The inhibition of [3H]dihydroalprenolol binding to rat heart, lung, and erythrocyte membrane preparations by these macromolecular derivatives was more than 1000-fold less potent than inhibition by alprenolol. The results suggest different structural characteristics between mammalian and amphibian beta-adrenoreceptors; however, apparently only small differences between mammalian receptors could be distinguished with these probes.

Alprenolol↗
PubMed1982

Muir-Torre syndrome: report of a case and reevaluation of the dermatopathologic features.

Muir-Torre syndrome patients have multiple internal malignancies along with cutaneous sebaceous proliferations and keratoacanthomas. We describe a 62-year-old male with nine primarily internal malignancies who survived eight years after his initial tumor was identified. His sebaceous lesions ranged from innocuous adenomas to an anaplastic carcinoma of the chin which recurred and spread locally to involve the mandible and the right parotid region.

Humans↗
PubMed1982

Probe for polyanionic regions on the cell surface.

The binding of polyuridylate to cells in the presence of proflavine may be used as a probe to provide relative estimates of exposed polyanionic regions on the external surface of the cell. This probe binds preferably to hydrophilic, polyanionic regions, and soluble polysaccharides containing either carboxylate or sulfate groups compete with the binding of this probe. Binding of the probe to protein and lipid regions is considerably weaker. Virus-transformed human fibroblasts bind 10 times less of the probe than nontransformed cells when confluent monolayers are compared. However, as the cell density is decreased, the amount of probe bound per cell increases dramatically both for transformed as well as for normal cells. In fact, human fibroblasts (a) derived from normal donors, (b) from donors with different metabolic disorders, and (c) transformed by simian virus 40, all bind about the same amount of probe when compared at the same density. Populations of human fibroblasts aged in vitro, which contain high proportions of large cells and grow only to relatively low densities in monolayers, bind disproportionately large amounts of the complex.

Cell Line↗
PubMed1982

Regeneration of beta-adrenergic receptors in senescent rats: a study using an irreversible binding antagonist.

The drug used in this study, bromoacetylalprenololmenthane, has the ability to bind and block irreversibly beta-adrenergic receptors. The drug was bound to membranes prepared from hearts, lungs, and brains of both senescent and young rats with a similar affinity. When this drug was injected into rats in nontoxic doses (up to 70 mg/kg), up to 90% of beta-adrenergic receptors were irreversibly blocked 4 hr after injection, whereas the injection of similar amounts of (+/-)-alprenolol was without effect on receptor number. In senescent animals this blockade lasted considerably longer than in young animals; receptor numbers in hearts and lungs of senescent rats returned to control levels only 1 month after injection. The number of beta-adrenergic receptors in brains of senescent rats was unaffected by this drug. Thus, based upon the long-lasting blockade of beta-adrenergic receptors in therapeutically important organs, it appears that irreversible binding blockers may have potential in the treatments of senescent organisms.

Adrenergic beta-Antagonists↗
PubMed1982

Irreversible blockade of beta adrenoreceptors and their recovery in the rat heart and lung in vivo.

The interaction of a bromoacetylated derivative of alprenolol (Alm-CO-CH2Br) with cardiac and lung beta adrenoreceptors was partially characterized. After a short incubation period, the concentration of Alm-CO-CH2Br that inhibited specific [3H]dihydroalprenolol binding by 50% in cardiac and lung membranes was 0.5 and 0.11 microM, respectively. The blockade was time-dependent and Scatchard analysis showed no change in the KD value for specific (-)-[3H]dihydroalprenolol binding but a loss of beta adrenoreceptor content after membrane pretreatment with Alm-CO-CH2Br. The blockade was not reversed by extensive membrane washing, although concurrent treatment with alprenolol fully protected whereas phentolamine had no protective effect. Alm-CO-CH2Br produced a dose-dependent blockade of heart and lung beta adrenoreceptors in vivo and the compound had little or no effect on the growth rate of the rat. Four hours after a single i.p. injection of Alm-CO-CH2Br at 35 mg/kg, the heart and lung beta adrenoreceptor content was decreased by 88 and 90%, respectively. The time required for complete recovery from irreversible beta adrenoreceptor blockade was about 200 hr in the heart and 650 hr in the lung. These results suggest that Alm-CO-CH2Br may be a useful probe for the beta adrenoreceptor both in vitro and for recovery studies in vivo.

Adrenergic beta-Antagonists↗
PubMed1981

Progressive nodular histiocytoma.

Progressive nodular histiocytoma is a clinically distinct variant in the general group of normolipemic histiocytic proliferations. Its cardinal feature is the presence of two different lesions--a superficial yellow-brown papule and a deep nodule. We describe herein a 29-year-old man with such lesions. Histologically, a variety of fibrous and cellular patterns were seen, mimicking the wide spectrum of findings in ordinary dermatofibromas. On ultrastructural examination, the most striking feature of the preponderant cell was lipid phagocytosis.

Adult↗
PubMed1980

Age-related decrease in repair of oxidative damage to surface sulfhydryl groups on rat adipocytes.

Adipocytes were isolated from the Wistar and Sprague-Dawley strains of rats of different ages. An impermeable reagent, mercury-[3H] dextran, was used to quantitate the sulfhydryl groups on the surface of these cells. The application of this reagent after the pre-reduction of cells with 2-mercaptoethanol yielded a measure of the total sulfhydryl and disulfide groups located there. Aging was found to significantly decrease the ratio of the number of exofacial sulfhydryl groups to the total number of exofacial sulfhydryl and disulfide groups.

Adipose Tissue↗
PubMed1980

Macromolecular beta-adrenergic antagonists discriminating between receptor and antibody.

The beta-adrenergic antagonist, alprenolol, was attached in an irreversible manner to macromolecular dextran via side arms that differed in length. The ability of these macromolecules to bind to the beta-adrenergic receptor of frog erythrocytes and to catecholamine-binding antibodies raised against partially purified receptors was studied. Compared to the parent drug the potency of binding of macromolecular alprenolol to the receptor decreased about 1/10, 1/600, and 1/8000 when the length of the arm separating alprenolol from the dextran moiety was 13, 8, and 4 atoms, respectively. In contrast, the binding potencies of the parent drug and of all its macromolecular derivatives for the antibody were within the same order of magnitude. Thus, conversion of a drug to a macromolecular form may not only sustain its binding activity but may also lead in a higher selectivity. The macromolecular derivatives described here may be suitable probes for investigation of the location and of the molecular properties of the binding sites for beta-adrenergic drugs.

Alprenolol↗
PubMed1980

Water-soluble, dextran-linked retinal: preparation, vitamin A-like activity in rats, and effects on melanoma cells.

A new, water-soluble, polymer-linked form of retinal was synthesized and tested for its ability to support the growth of vitamin A-deficient noninbred Holtzman rats and to inhibit the proliferation of melanoma cells in culture. Retinal was conjugated to the hydrazide of carboxymethyldextran in the presence of alpha-and beta-cyclodextrins. The aqueous solutions of the product contained between 200 and 1,000 micrograms retinal/ml as opposed to the low water solubility (< 0.01 micrograms/ml) of retinal itself. The retinal-dextran complex, although barely resorbed from the gastrointestinal tract, supported the growth of rats fed a vitamin A-deficient diet when administered ip at 2.3 mumol of retinal equivalent/kg body weight. Retinal and the retinal-dextran complex exhibited differential cytotoxicity toward S91 melanoma cells and caused cell lysis at 10 and 500 microM (retinal residue), respectively. At noncytotoxic doses both free retinal and its dextran-linked derivative reduced the cell proliferation rate in a time- and dose-dependent fashion with median inhibitory doses of 1 and 4 microM (retinal residue), respectively. These data demonstrated that the water-soluble retinal-dextran complex retained certain biologic activities of retinal and was less cytotoxic.

Animals↗
PubMed1979

Mechanism of enhancement of polynucleotide binding to cells by mutagens.

The binding of polyuridylate to cells is substantially increased by proflavine. This enhanced binding is saturable with respect to time and to the concentration of both proflavine and polyuridylate. Enhancement is observed only when cells are exposed to both proflavine and polyuridylate together and depends cooperatively on the proflavine concentration. The resulting complex formed between the cell, proflavine, and polyuridylate can be dissociated with salt but not with sucrose solutions. An increase in the binding of polyuridylate to cells similar to that observed with proflavine was also obtained with cationic dyes such as acridine orange, 9-aminoacridine, and Hoechst 33258, while the introduction of a bulky polysaccharide residue, dextran, into the dyes cancels these effects. Similarly, cationic aromatic compounds such as primaquine and quinacrine which carry bulky nonplanar substituents or aliphatic cationic compounds like ethylenediamine do not enhance binding. Proflavine is unable to augment the binding of a basic macromolecule, diethylaminoethylaminoethyldextran, to cells. The model proposed for the enhanced binding of polyuridylate is based on the cooperative formation of stacked complexes of cationic dye located between the cell surface and the bound polyuridylate.

Cell Line↗
PubMed1979

Adenocarcinoma of rete testis.

Adenocarcinoma of the rete testis is a rare tumor of the genital tract. An advanced case of adenocarcinoma thought to arise from the rete testis is presented. We believe this is the eighteenth reported case.

Adenocarcinoma, Papillary↗