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Biomedical subjects

M T Martin

Publications and source records attributed to M T Martin.

90 records · Page 5Linked to original sources
PubMed1980

Staining and histochemistry of undecalcified bone embedded in a water-miscible plastic.

Undecalcified bone fixed in a variety of fixatives and embedded in a new formulation of 2-hydroxypropyl methacrylate at 4 c has been sectioned at 1 to 5 microns. The embedding mixture contains 2-butoxyethanol as plasticizer and triethyleneglycol dimethacrylate as cross-linker. The accelerator was benzoyl peroxide and the catalyst was N,N-dimethylaniline. With proper embedding and care in sectioning it is possible to obtain sections with relatively little bone compression, excellent preservation of cellular elements, and a minimum of wrinkling. A wide variety of stains have been used for these sections and those reported here are Gill's hematoxylin-eosin, Nocht's azure-eosin, Feulgen, Hoechst 33258 (bisbenzimid H 33258), methyl green-pyronin, PAS, alizarin red, and von Kossa silver stain. There was excellent preservation of acid and alkaline phosphatase activities. A new method of prestaining immunofluorescent labeling was also applied to bone and examples of staining with anticollagen I and antifibronectin are presented.

Animals↗
PubMed1980

A novel method to improve immunofluorescence in histological specimens.

A new approach to immunofluorescent labeling of sectioned tissue is described. Small tissue fragments which have been fixed and rendered permeable are labeled with immune reagents by either the direct or indirect method, prior to embedding in glycol methacrylate (2-hydroxyethyl methacrylate) at 4 degrees. In this way, the well-known superiority of plastic embedding over paraffin embedding or cryo-sections can be used to compare cellular structure in tissues with that seen in cultured cells.

Animals↗
PubMed1979

Abdominal cryptorchidectomy in the horse, using inguinal extension of the gubernaculum testis.

Removal of abdominal testes was accomplished in 32 horses ranging in age from 6 to 72 months. Twenty were unilateral and 12 were bilateral abdominal cryptorchids. An incision was made over the superficial inguinal ring, and the extension of the gubernaculum testis was identified and grasped with forceps. Traction was applied to this structure until the vaginal process was everted beyond the superficial inguinal ring. The vaginal process was incised and the protruding structure, usually the epididymis, was grasped. The testis was drawn out by gentle traction on the epididymis, and castration was performed in the routine manner.

Animals↗
PubMedDate not supplied

Reversible and irreversible immobilization of enzymes on Graphite Fibrils.

Graphite Fibrils are hollow tubes (0.01 x 1-10 microns) consisting of concentric layers of graphite. Fibrils can be chemically modified to introduce surface functionalities such as carboxyl groups. Carboxylated fibrils were further functionalized to amino alkyl derivatives which were covalently linked to an enzyme, horseradish peroxidase (HRP). HRP fibrils showed substantial catalytic activity. Additionally, carboxyl fibrils were derivatized with specific inhibitors of the enzymes beta-galactosidase (beta-Gal) and alkaline phosphatase (AP). Enzyme inhibitor-modified fibrils were used to specifically purify both beta-Gal (using beta-Gal inhibitor fibrils) and AP (using AP inhibitor fibrils) from mixtures of these two enzymes. These studies demonstrate the feasibility of using Graphite Fibrils as supports in biocatalysis and biospecific affinity chromatography.

Alkaline Phosphatase↗
PubMedDate not supplied

Aspects of antibody-catalyzed primary amide hydrolysis.

Because there are many known C-terminally amidated peptides of biological importance, there is great potential in medicine and organic synthesis for antibodies that catalyze primary amide bond hydrolysis or formation. We characterized a catalytic antibody, 13D11, raised to a phosphinate hapten, that hydrolyzed the primary amide of a dansyl-alkylated derivative of (R)-phenylalaninamide (DNS-(R)F-NH2). At pH 9.0, 13D11 hydrolyzed DNS-(R)F-NH2 with a kcat of 1.65 x 10(-7) s-1 (kcat/kuncat = 132) and a Km of 432 microM, and was stereospecifically hapten-inhibited (Ki = 14.0 microM). Control experiments indicated that the catalytic activity was not the result of a contaminating protease. In accordance with the hapten being a transition-state analog of base hydrolysis, the rate of DNS-(R)F-NH2 hydrolysis increased with hydroxide concentration to an optimum pH of 9.5. Above pH 9.5, activity declined rapidly suggesting the antibody was inactivated during the long incubation period. This work demonstrates the feasibility of generating catalytic antibodies to hydrolyze unactivated amide bonds without cofactor assistance.

Amides↗
PubMedDate not supplied

An efficient, scalable synthesis of the HIV reverse transcriptase inhibitor Ziagen (1592U89).

Ziagen, (1S,cis)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]- 2-cyclopentene-1-methanol, was synthesized from (1S,4R)-azabicyclo[2.2.1]hept-5-en-3-one by efficient processes which bypass problematic steps in earlier routes. 2-Amino-4,6-dichloro-5-formamidopyrimidine is a key intermediate which makes possible an efficient construction of the purine from a chiral cyclopentenyl precursor.

Anti-HIV Agents↗
PubMedDate not supplied

Melatonin and the gastrointestinal tract.

Melatonin has been detected in the digestive tract of several species and appears to be synthesized by the enterochromaffin cells of the gut. Although a diurnal rhythm of melatonin release has been observed in gastrointestinal tissues of birds, in other species it seems to depend on the presence of nutritional elements. Melatonin binding sites have been identified in the digestive tract of several species and it has been suggested that melatonin could act as a protecting agent of the gastrointestinal mucosa. Moreover, the potential role of melatonin as a local regulator of gastrointestinal motility has been investigated. It seems that at least some effects of melatonin on gut activity depend on an antagonistic relationship between serotonin and melatonin. The effects of melatonin on segmental gut transit both in the fasting and in the fed state, as well as on the electromyographic pattern of the small intestine in rats, are described.

Animals↗