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C Cain

Publications and source records attributed to C Cain.

15 recordsLinked to original sources
PubMed1995

Modes of photodynamic vs. sonodynamic cytotoxicity.

We compared effects of ultrasound-induced vs. photodynamic cytotoxicity in cell culture. The photodynamic effects mediated by mesoporphyrin caused a delayed toxic reaction, the presence of a "shoulder" on the dose-response curve, indicating the capacity for limited repair of photodamage. In contrast, ultrasound-induced loss of viability resulted from rapid cell destruction and was proportional to the time of sonication. Photodynamic damage to cells before exposure to ultrasound potentiated cell breakage but did not affect the clonogenicity of the surviving cell population. Photodamage after exposure to ultrasound decreased the viability of cells which had survived ultrasonic treatment.

Animals↗
PubMed1994

Porphyrin-induced enhancement of ultrasound cytotoxicity.

We examined the effect of ultrasound on the murine leukaemia L1210 cell line in culture, in the presence of porphyrins varying widely in their capacity to sensitize cells to light. These porphyrins enhanced ultrasound-induced cell damage in vitro only when present in the incubation medium. When cells containing intracellular porphyrins were exposed to ultrasound, cell viability was not altered. Moreover, there was no correlation between the efficacy of a given porphyrin for light- versus ultrasound-induced cytotoxicity. Loss of viability was associated with inhibition of amino acid transport and cell fragmentation, suggesting disruption of the integrity of the cell membrane. Ultrasound-induced cell damage occurred only in the presence of cavitation nuclei.

Animals↗
PubMed1994

Moisture content of vital vs endodontically treated teeth.

The moisture content of vital and endodontically treated teeth was compared in matched pairs of contralateral human teeth extracted for prosthodontic reasons. Samples from each tooth were weighed then placed in an oven to remove the unbound water from the dentin. Weighing was carried out daily until a constant weight was achieved for three days. The moisture content was then calculated and expressed as a percentage of the initial sample weight. It was found that vital dentin had a moisture content of 12.35% whilst dentin from endodontically treated teeth had a moisture content of 12.10%. These results indicated that there was no significant difference in the moisture content between endodontically treated teeth and vital teeth.

Adult↗
PubMed1994

S-100 protein-negative malignant melanoma: fact or fiction? A light-microscopic and immunohistochemical study.

S-100 protein is considered a characteristic immunohistochemical marker for all nevomelanocytic lesions, in which it is expected to be present consistently. We reviewed 17 cases of malignant melanomas that previously tested negative for S-100 protein. They were reevaluated by light microscopy, a broad panel of immunohistochemical reagents including monoclonal and polyclonal antibodies to S-100 protein, and electron microscopy. On reexamination, five of the 17 cases were reclassified as non-melanoma tumors, and eight of the 17 cases were found to be positive for S-100 protein (six with monoclonal and eight with polyclonal antibodies) and HMB-45 antigen, consistent with melanoma. The remaining four cases repeatedly tested negative for S-100 protein despite various antigen enhancement methods, but they were positive for HMB-45 antigen and contained premelanosomes or melanosome-like structures by electron microscopy. Two of these repeatedly S-100 negative melanomas were acrally located; although the numbers are small, a possible relationship to a specific anatomic location cannot be excluded. These findings suggest that in a small subset of melanomas S-100 protein is either not fully expressed or is below the level that can be detected by routine immunohistochemistry. We also conclude that in the majority of the initially S-100-negative cases of melanomas, the misdiagnosis may occur due to the use of an incomplete immunohistochemical panel, technical reasons, or the inherent variability of tissue expression of S-100 protein.

Antigens, Neoplasm↗
PubMed1993

Efficacy of tunnel restorations in the removal of caries.

Tunnel restorations have been advocated as a conservative treatment modality for early carious lesions. However, the question arises as to quantity of dentin that remains within the marginal ridge above the tunnel path. In this experiment, extracted maxillary premolars with early carious lesions were sectioned and photographed. Measurements taken from tracings of the projected slides revealed that no dentin remained within the marginal ridge, irrespective of the direction of the tunnel path. These measurements indicate that the tunnel restoration is not a satisfactory treatment for proximal caries. The position of caries precludes the cutting of a tunnel preparation that leaves sufficient dentin under the marginal ridge, unless the bulk of enamel caries is left untouched.

Bicuspid↗
PubMed1993

Tunnel restorations versus class II restorations for small proximal lesions: a comparison of tooth strengths.

An increased emphasis on the preservation of tooth structure has led to alternative cavity designs for early proximal caries. The tunnel restoration (which preserves the marginal ridge) and a conservative Class II composite resin restoration were compared in vitro for effects on tooth strength with nondestructive and destructive tests. The tunnel restoration, which is generally thought to be the more conservative of the two techniques, was actually more damaging, as shown by the stiffness, load at fracture, and proximity to the pulp.

Analysis of Variance↗
PubMed1986

Alpha 1-adrenergic and H1-histamine receptor control of intracellular Ca2+ in a muscle cell line: the influence of prior agonist exposure on receptor responsiveness.

Activation of alpha 1-adrenergic receptors in BC3H-1 muscle cells has been shown previously to mobilize intracellular Ca2+, which can be monitored as enhanced 45Ca2+ unidirectional efflux. We report here that histamine also stimulates 45Ca2+ efflux in these cells (Kact = 5.50 microM, nH = 0.94 +/- 0.04), reflecting mobilization of intracellular Ca2+ from a source similar to that accessed by alpha 1-adrenergic receptor activation. In addition, histamine stimulates substantial transmembrane 45Ca2+ influx into BC3H-1 cells. The actions of histamine are inhibited by the H1-selective antagonist, diphenhydramine (IC50 = 1.01 microM), but are unaffected by the H2-selective antagonist, cimetidine (1 nM-10 microM) indicating that histamine regulates cellular Ca2+ via a functional H1 receptor. The presence of independent receptor types which mobilize Ca2+ originating from common intracellular stores has been exploited in order to evaluate the determinants of receptor responsiveness following prior agonist exposure. After exposure with 45Ca2+ to achieve radioisotopic equilibrium, 30 min incubation with increasing concentrations of norepinephrine reduces to similar extents (30-40%) the unidirectional 45Ca2+ efflux responses to subsequent challenges by maximally effective concentrations of norepinephrine or histamine. The decrement in response following norepinephrine exposure appears to reflect an altered disposition of agonist-sensitive intracellular Ca2+, whereas the concentration dependence for alpha 1-adrenergic receptor activation remains unchanged. Prior exposure of cells to increasing concentrations of histamine also reduces the efflux response to norepinephrine challenge (approximately 30% decrease), whereas the response to subsequent histamine challenge is specifically and completely abolished. The loss of histamine responsiveness is accompanied by a marked shift in the concentration dependence for histamine receptor activation toward higher histamine concentrations. These results indicate that substantial alpha 1-receptor responsiveness is maintained following agonist exposure and that the observed reduction in response occurs distally to the receptor itself at some point common to alpha 1- and H1-receptor-effector coupling. By contrast, the H1-histamine receptor exhibits refractoriness, indicative of agonist-induced receptor desensitization.

Animals↗
PubMed1984

Purification and characterization of a lysophospholipase from human amnionic membranes.

We have identified the presence of a lysophospholipase in human placental tissues and have purified this enzyme from the amnion. The specific activity was highest in the amnion and decreased across adjacent tissues. The purification involved the use of DEAE-Sephadex, phenyl-Sepharose, hydroxylapatite, and sulfylpropyl Sephadex chromatography. The activity of the purified enzyme toward palmitoyl lysophosphatidylcholine is 2.5 mumol min-1 mg-1 and the pH optimum is 7.0. The enzyme is not inhibited by EDTA and does not appear to have a metal ion requirement. The enzyme may be of membrane origin; the purified enzyme requires the presence of detergent during storage. The effects of substrate composition and physical state on enzymatic activity were explored. The enzyme was not active toward mono-, di-, or triglycerides, nor toward diacyl phospholipid. The enzyme was active toward myristoyl and palmitoyl lysophosphatidylcholine at concentrations where these substrates spontaneously form micelles or where Triton X-100 was used to induce co-micellization of the substrate at low concentrations with detergent. A role for this enzyme in processing the lysophospholipid product of phospholipase A action must be considered in evaluating arachidonic acid production in human fetal membranes and placental tissue, particularly during the initiation of labor.

Amnion↗
PubMed1980

Sex differences in predictors of antisocial behavior in adoptees.

The present study follows up adoptees separated at birth from the biologic parents to assess the importance of genetic and environmental factors in adolescent antisocial behavior. The dependent variable is an antisocial symptom count that tallies antisocial but not necessarily criminal behaviors in adolescence. The independent variables are of two types, genetic and environmental. Genetic variables refer to psychiatric diagnoses of the biologic family. Environmental variables are those identified by previous research as associated with adolescent antisocial behavior. Our results indicate that boys are more vulnerable than girls to the adverse effects of a psychiatrically ill adoptive family member or divorce in the adoptive parents. There is not a significant sex difference in genetic predictors. In the total sample, the genetic variables that predict antisocial behavior are having an antisocial or alcoholic biologic relative. This finding is in agreement with other heritability studies of antisocial behavior.

Adolescent↗