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Biomedical subjects

D S Martin

Publications and source records attributed to D S Martin.

At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

Age-related changes in LTP and antioxidant defenses are reversed by an alpha-lipoic acid-enriched diet.

Among the age-related changes identified in rat hippocampus are impairments in LTP and glutamate release. These deficits have been coupled with decreased arachidonic acid concentration. In this study we compared LTP and glutamate release in groups of aged and young rats fed for 8 weeks on a control diet or on a diet enriched in alpha-lipoic acid. Dietary supplementation in aged rats restored hippocampal arachidonic acid concentration to levels observed in tissue prepared from young rats. We observed that aged rats that received the experimental diet sustained LTP in perforant path-granule cell synapses in a manner indistinguishable from young rats whereas the age-related impairment in glutamate release was reversed in synaptosomes prepared from dentate gyrus obtained from these rats. The evidence presented supports the hypothesis that the alpha-lipoic acid-enriched diet has antioxidant properties, because the age-related increase in superoxide dismutase activity and decrease in alpha-tocopherol concentration were reversed. The finding that the age-related increase in interleukin-1 (IL-1)beta concentration was also reversed suggests a possible role for this cytokine in ageing.

Aging↗
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A concomitant ATP-depleting strategy markedly enhances anticancer agent activity.

Most anticancer agents effect DNA damage which initiate the cell death pathways of necrosis and apoptosis, but cancer cells of lesser sensitivity are only sublethally injured, and recover. The two death pathways and their interelationships in the presence of endogenous inhibitors of apoptosis and genetic deletions that facilitates only sublethal damage, are reviewed. Both ATP and pyrimidine levels in the sublethally injured cancer cells are reduced but not to low levels insuffient to sustain cell viability. However, this sublethal damage by the anticancer agent creates a therapeutic opportunity for further reduction of these key metabolites to lower levels that will not support life. Data in tumor-bearing animals is reviewed demonstrating that a combination of ATP-depleting agents plus a de novo pyrimidine inhibitor (PALA) administered concomitantly with each of nine different anticancer agents markedly enhances tumor regression rates,and even produces some cures. It is necessary to deplete tumor ATP levels seveerely (>85%) by a combination of agents that block both synthesis (6-methylmercaptopurine riboside, a purine de novo synthesis inhibitor) and generation of ATP(6-aminonicotinamide, an inhibitor of glycolysis.) Cell viability cannot be sustained if the intracellular ATP level is reduced to 15% of normal or below. In vivo data employing this novel therapeutic strategy with cisplatin is presented. The potential significance of these findings to the improvement of cancer treatment is discussed.

Adenosine Triphosphate↗
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MR imaging of lumbar juxtaarticular cysts.

Three surgically proven cases of lumbar extradural juxtaarticular cysts were examined by magnetic resonance (MR) imaging. The highly variable MR signal patterns are presented.

Adult↗
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Fat deposition adjacent to chronic subdural hematoma: CT demonstration.

Computed tomography of the head in a patient with bilateral chronic subdural hematomas demonstrated areas of fat density closely approximating the hematomas. The persistent fatty nature of the CT finding was confirmed by subsequent magnetic resonance and CT performed 1 month and 3 years later. Although an intracerebral hemorrhage with transient presence of fatty material has been described in an alcoholic hyperlipemic patient, this case shows fatty deposition adjacent ot subdural hemorrhage without any known predisposing factors.

Adipose Tissue↗
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A light and electron microscopic study of Trypanosoma fallisi N. Sp. in toads (Bufo americanus) from Algonquin Park, Ontario.

Trypanosoma fallisi n. sp. is described from Bufo americanus in Ontario. The parasite was observed in 65 of 94 toads examined. The trypanosomes were pleomorphic with respect to the age of infections, being longer and broader in early infections (during spring and summer) and shorter and more slender during late summer and autumn. They ranged in size from 38-76 microns in body length and 3-8 microns in width, with a free flagellum 6-30 microns long. Epizootiological and experimental evidence suggests that this trypanosome is transmitted to the toads by the leech, Batracobdella picta. Trypanosoma fallisi is morphologically similar to T. bufophlebotomi described in Bufo boreas from California, but geographic isolation, host and vector differences as well as slight morphological differences indicate that speciation has occurred. Similar trypanosomes from Bufo americanus (which were identified as T. bufophlebotomi) in Michigan, are probably T. fallisi. This species shares many ultrastructural features with trypanosomes of other lower vertebrates and also of mammals.

Animals↗
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Phylogenetic relationships among anuran trypanosomes as revealed by riboprinting.

Twenty trypanosome isolates from Anura (frogs and toads) assigned to several species were characterized by riboprinting-restriction enzyme digestion of polymerase chain reaction amplified small subunit ribosomal RNA genes. Restriction site polymorphisms allowed distinction of all the recognized species and no intraspecific variation in riboprint patterns was detected. Phylogenetic reconstruction using parsimony and distance estimates based on restriction fragment comigration showed Trypanosoma chattoni to be only distantly related to the other species, while T. ranarum and T. fallisi appear to be sister taxa despite showing non-overlapping host specificities.

Animals↗
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Fine needle aspiration biopsy of well-differentiated liposarcoma of the neck in a young female. A case report.

BACKGROUND: Well-differentiated liposarcomas are low grade, nonmetastasizing, malignant neoplasms composed primarily of mature adipose tissue. They are uncommon in the head and neck. CASE: A 24-year-old female presented to the ears, nose and throat clinic for evaluation of a recent, rapidly growing neck mass on the right side. Fine needle aspiration (FNA) biopsy of the mass showed that the smears had fragments of connective tissue with a mixture of mature-appearing fat traversed by bands of fibrous collagen and vessels. Nuclei within the fat and fibrous bands were mildly irregular, hyperchromatic and enlarged, with one or two small nucleoli. Infrequently present but readily identified, lipoblasts were scattered throughout the aspirate smears. A diagnosis of "atypical lipomatous neoplasm" was rendered. Subsequently, the mass was surgically removed. On histologic examination, the tumor was a well-differentiated liposarcoma. CONCLUSION: FNA biopsy of well-differentiated liposarcomas in the head and neck can present difficulties in the classification and diagnosis of this neoplasm.

Adult↗
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Color threshold and ratio of S100 beta, MAP5, NF68/200, GABA & GAD. I. Distribution in inner ear afferents.

Afferents of chick embryos (Gallus domesticus) VIIIth nerve were examined at E3, E6, E9, E13, El7, and hatching (NH) for anti-S100 beta, anti-MAP5, anti-GABA, anti-GAD and anti-NF68/200 stain. Different ages were processed together to determine if the distribution of these antibodies changed during synaptogenesis and myelination. Color thresholding showed that saturation of pixels changed for S100 beta only 5%, for NF68/200 10%, and for MAP5, 10%, between E9-NH. Color ratio of NF68/200 over MAP5 was 1.00 at E13 and 0.25 at E16 and NH. S100 beta, GABA and GAD were co-expressed on nerve endings at the edge of the maculae and center of the cristae, whereas hair cells in the center of the maculae expressed either S100 beta or GABA, but not both. S100 beta/NF68/200 shared antigenic sites on the chalices, but NF68/200 expression was higher than S100 beta in the chalices at hatching. MAP5 was expressed in more neurons than NF68/200 at E11, whereas NF68/200 was more abundant than MAP5 at hatching. The results suggest that: 1) the immunoexpression of these neuronal proteins is modulated concomitantly with the establishment of afferent synapses and myelination; 2) S100 beta may serve a neurotrophic function in the chalices where it is co-expressed with the neurotransmitter GABA and its synthesizing enzyme GAD.

Animals↗
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The nuclear trial sign in thoracic herniated disks.

PURPOSE AND METHODS: Postmyelography CT studies of 84 patients with 114 thoracic herniated disks were reviewed for endplate irregularity, sclerosis, and/or disk-space calcification that could suggest a migratory path of the herniated fragment. RESULTS: Abnormal straight or curvilinear densities (the "nuclear trial sign") were present at the level of the disk or endplate in 46% of the cases. MR studies of 35 thoracic herniated disks were also examined. Similar changes were likewise present in 44%. CONCLUSION: The frequent occurrence of this finding in the mid and lower thoracic spine renders it a useful secondary sign for thoracic herniated disks, although false positives do occur.

Humans↗
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N-acetylcysteine in the treatment of human arsenic poisoning.

A 32-year-old man was brought to the emergency department 5 1/2 hours after ingesting a potentially lethal dose (900 mg) of sodium arsenate ant poison in a suicide attempt. The patient deteriorated progressively for 27 hours. After intramuscular dimercaprol and supportive measures failed to improve his condition, he was given N-acetylcysteine intravenously. The patient showed remarkable clinical improvement during the following 24 hours and was discharged from the hospital several days later.

Acetylcysteine↗