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Biomedical subjects

J Dunn

Publications and source records attributed to J Dunn.

At least 199 records · Page 11Linked to original sources
PubMed1986

Cloning of the esterase D gene: a polymorphic gene probe closely linked to the retinoblastoma locus on chromosome 13.

The study of recessive oncogenes such as those responsible for retinoblastoma and Wilms tumor is difficult because the gene products involved are unknown and because the diseases are not associated with unique cellular or molecular phenotypes suitable for genetic manipulation. Since the gene for esterase D (ESD) is known to be tightly linked to the retinoblastoma locus (RB1) in the q14.1 band of chromosome 13, we have cloned the ESD gene from a human cDNA library by using oligonucleotides specific for a partial amino acid sequence of the purified enzyme to provide a genetic marker for further studies on retinoblastoma. The putative ESD gene codes for a message of 1.2 kilobases, which is present in all cell types examined, and maps to 13q14.1, thus confirming that it is the ESD gene. Restriction enzyme analysis reveals a restriction fragment length polymorphism with Apa I; this polymorphism results from the heterozygosity of 32% of the individuals tested and is shown to be useful in identifying carriers of the mutation responsible for retinoblastoma. A preliminary screen of 24 retinoblastoma tumors by Southern blot did not reveal any homologous deletions or rearrangements of the ESD locus.

Carboxylesterase↗
PubMed1986

Sibling quarrels and maternal intervention: individual differences in understanding and aggression.

Individual differences in the nature and frequency of conflict behaviour between 18-24 month old children and their older siblings were investigated in a sample of 43 sibling pairs observed at home with their mothers. By 24 months, relatively mature behaviour such as conciliation, teasing, reference to social rules and justification for prohibition were observed. These behaviours were correlated with maternal and sibling reference to social rules and feelings 6 months earlier; physical aggression was correlated with earlier sibling physical aggression and maternal involvement. Sibling status and type of maternal intervention were not related to frequency and duration of sibling conflict.

Aggression↗
PubMed1985

Posterior mediastinal teratomas.

Eight benign posterior mediastinal teratomas have been found in the world's literature. Including our case, four teratomas were intimately involved with, and often required, partial resection of the major surrounding structures--aorta, chest wall, and esophagus. Preoperative evaluation of posterior mediastinal teratomas should include consideration of a barium swallow and/or aortography to rule out significant local involvement.

Esophagus↗
PubMed1985

Continuities in sibling relationships: patterns of aggression and friendliness.

Thirteen girls and 12 boys who had been observed at home as 2- to 3-year-olds with their mothers and infant siblings were interviewed as 6-year-olds about their relationship with their siblings; their mothers also were interviewed. The marked individual differences found among the 2- to 3-year-olds in comments about their siblings were correlated with differences in the children's comments about their siblings 3-4 years later, and the differences in their behaviour towards their siblings as 2- to 3-year-olds were correlated with differences in their mothers' accounts of the sibling relationship at the 6-year visits.

Aggression↗
PubMed1985

Environmental differences within the family and adjustment differences within pairs of adolescent siblings.

To what extent do siblings in the same family experience different parental treatment, sibling interaction, and peer relationships? Are such within-family experiential differences related to differences in the siblings' emotional adjustment? The present study explored these questions concerning within-family environment using data from 348 families that each included 2 siblings 11-17 years of age. The results indicate that siblings in the same family experience different environments, as reported by parents and to a larger extent by the siblings themselves. The results also demonstrate that within-family environmental differences are related to differences in development between siblings. Both the parent and sibling reports of the environment converge on the finding that the sibling who is more psychologically well adjusted (as reported by parents, siblings, and teachers) also experiences more maternal closeness, more sibling friendliness, more peer friendliness, more say in family decision making, and more parental chore expectations as compared to the other sibling.

Adolescent↗
PubMed1984

Association of gap junctions with endoplasmic reticulum in rat parotid glands.

Examination of the parotid gland of the rat has shown specific associations of cisterns of the endoplasmic reticulum with gap junctions. About 20% of the junctions are so intimately associated with cisterns of the endoplasmic reticulum that in freeze fractured material the cisternal membranes remain attached to the junctional membrane faces, obscuring most of the junctional array except for a thin ring of telltale particles. This association was seen only in the parotid gland of the rat, but not that of the other species examined.

Animals↗
PubMed1984

Taenia crassiceps: temperature, polycations, polyanions, and cysticercal endocytosis.

The effect of various temperatures, poly-L-lysine, and poly-L-glutamic acid on endocytosis of smooth micropinocytotic vesicles (pinosomes) in the tegument of the cysticercus of Taenia crassiceps has been investigated stereologically. The temperature regimes used were 0, 5, 10, 20, 30, and 40 C. Maximum volume, surface density, and number per unit volume were found at 40 C, and minimum surface-to-volume ratio and numbers at 10 C. At 10 C, mean pinosome volume and mean surface area per pinosome were maximal, but volume and surface density did not differ significantly from 40 C. It is proposed that this anomalous finding for 10 C incubations was due to this being a critical temperature at which a slower rate of pinosome formation was compensated for by the formation of larger individual pinosomes. Poly-L-lysine was shown to be a stimulant of pinosome formation, leading to a significant increase in numbers per unit volume. However, volume and surface density, surface-to-volume ratio, mean volume, and mean surface area per pinosome were not significantly different in poly-L-lysine-incubated samples, when compared to controls (fresh from the mouse) or incubations in medium only or samples returned to medium after poly-L-lysine incubation, the only exception being surface to volume ratio and mean volume of pinosomes in the 75-min incubation. These anomalous results were explained by a marked reduction in the form ellipse values, which indicated the production of more elliptical-shaped pinosomes under poly-L-lysine stimulation. Incubation in poly-L-glutamine acid did not have any significant effect at any incubation time.

Animals↗
PubMed1984

Taenia crassiceps: basic mechanisms of endocytosis in the cysticercus.

The effects of glucose, yeast extract, fetal bovine serum albumin, and ruthenium red on endocytosis of smooth micropinocytotic vesicles (pinosomes) in the tegument of the cysticercus of Taenia crassiceps have been investigated stereologically. Glucose has been shown to stimulate pinocytosis, whether it was used alone or in combination with yeast extract or bovine serum albumin. Yeast extract was a stimulant of endocytosis. Bovine serum albumin was the most potent stimulant of all the substances investigated in this study. Although the time of incubation in ruthenium red was the same for all incubation experiments, varied numbers of ruthenium red-containing pinosomes were observed in different experiments. The role of ruthenium red as a stimulant and/or initiator of endocytosis and the possible explanations for differences in ruthenium red uptake are discussed.

Animals↗
PubMed1984

Discovery, purification and characterization of the angiotensin converting enzyme inhibitor, L-681,176, produced by Streptomyces sp. MA 5143a.

L-681,176, an inhibitor of angiotensin converting enzyme was found in the culture filtrate of Streptomyces sp. MA 5143. The I50 of the crystalline inhibitor is about 1.3 micrograms/ml and the inhibition is reversed by zinc sulfate. In rats, L-681,176 exhibits a dose-related inhibition of the pressor response to angiotensin I with an ID50 of 142 mg/kg when administered intravenously. The structure of L-681,176 is similar to that of marasmine but lacking one carboxyl group. The maximum yield of L-681,176 occurs after three to four days growth at 28 degrees C.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1983

The effect of surfactants on the interaction of factor XII with surfaces.

Factor XII (Hageman factor) binds irreversibly to plastic as well as glass surfaces. In dilute solution this leads to significant losses of protein onto the walls of tubes, etc. This could be prevented most efficiently by the presence of surfactants in solution. Rinsing the surfaces after contact with the protein, or precoating the surfaces were less effective. Triton X-100 was found to be non-denaturing and effective at concentrations as low as 0.001%. In its presence higher specific activities were obtained in spectrophotometric assay. The autoactivation of factor XII exposed to glass was inhibited but not prevented by Triton X-100. Similar effects on the binding and assay of (Pre) kallikrein were also found.

Detergents↗
PubMed1983

Bilateral lesions of suprachiasmatic nuclei affect circadian rhythms in [3H]-thymidine incorporation into deoxyribonucleic acid in mouse intestinal tract, mitotic index of corneal epithelium, and serum corticosterone.

Investigations into the role of the suprachiasmatic nuclei (SCN) in the coordination of circadian rhythms have presented differing results. Several reports have shown that ablation of the suprachiasmatic nuclei (SCNA) alters the phase and amplitude of rhythms but does not abolish them. The present study investigates the effect of SCNA on the rhythms in cell proliferation in various regions of the intestinal tract as measured by the incorporation of [3H]-thymidine into deoxyribonucleic acid, in the mitotic activity of the corneal epithelium, and in serum corticosterone levels. The study involved mice with verified lesions of the SCN (six to 13 mice per time point) and control groups of both sham-operated and unoperated mice (seven of each per time point). The mice were killed in groups that represented seven time points over a single 24 hr span (3 hr intervals with the 0800 hr sampled both at start and end of the series). The tissues examined were the tongue, esophagus, gastric stomach, and colon for DNA synthesis, the corneal epithelium for mitotic index, and blood serum for corticosterone level. The most consistent result of SCNA was a phase advance in the rhythms in cell proliferation in the tongue, esophagus, gastric stomach, colon, and corneal epithelium. A reduction in rhythm amplitude occurred in the tongue, esophagus, and corneal epithelium; however, there was an amplitude increase for the stomach, colon, and serum corticosterone. The mesor (rhythm-adjusted mean) was increased by SCNA in all tissues except the corneal epithelium. These findings further support the role of the suprachiasmatic nuclear area in the control of rhythms in cell proliferation and corticosterone production, by acting as a "phase-resetter" and as a modulator of rhythm amplitude.

Animals↗
PubMed1983

Taenia crassiceps: regional variations in ultrastructure and evidence of endocytosis in the cysticercus' tegument.

Regional variations in the thickness of the tegument, in the morphology of microtriches and mitochondria, in the distribution of dense bodies, smooth micropinocytotic vesicles (SMVs), and coated micropinocytotic vesicles (CMVs) have been shown for the cysticercus of Taenia crassiceps. The number of SMVs and CMVs present in the syncytial layer are in inverse proportion to each other, the former being more numerous in the bladder wall and upper part of the invagination canal and the latter in the lower part of the canal and the rostellar region. Tegumental cells contain numerous granular endoplasmic reticulum-Golgi complexes involved in the synthesis of both primary lysosomes and dense bodies. Vesicles characteristic of various stages of heterolysosomes are present and show regional variations in numbers and size. Acid phosphatase activity (EC 3.1.3.2) is present on the tegumental surface, and within the Golgi complex, primary lysosomes, and heterophagosomes of the tegumental cells. CMVs are reported for the first time in the tegument of any helminth and have characteristics similar to CMVs in other tissues. T. crassiceps, therefore, because of the presence of both SMVs and CMVs, is a unique model system for the study of basic mechanisms of endocytosis.

Animals↗
PubMed1982

Etretinate in treatment of actinic keratosis. A double-blind crossover study.

50 patients with actinic keratosis were studied over four months of treatment with either etretinate ('Tigason') or placebo. Each treatment was given for two months and the order of administration was randomised. The clinical response to treatment was assessed by direct measurement and photographs of the lesions at monthly intervals. Of the 44 patients who completed treatment with etretinate 37 had a complete or partial response. Of the 42 patients who completed treatment on placebo only 2 showed a complete or partial response. The response to treatment occurred within the first month of therapy and was maintained even when the dose was reduced because of toxicity.

Aged↗
PubMed1982

Factors affecting the practice of circumcision.

In 1975, the American Academy of Pediatrics (AAP) stated that there is "no medical indication for routine circumcision of the newborn." A survey was conducted among Chicago-area pediatricians, obstetricians, and family practitioners to determine what impact this statement had on their approach to circumcision. Hospitals were also surveyed to determine whether the AAP's statement had caused a change in the frequency of circumcision in area hospitals. Only 49% of the physicians were aware of the AAP's position. Forty-one percent recommended routine circumcision; 15% recommended against the practice. Age, medical specialty, religious customs, and concerns about hygiene and cancer all appeared to influence the physicians' approach to circumcision. The frequency of routine circumcision. The frequency of routine circumcision was 70% to 90% and remained unchanged in the three years following the AAP's statement.

Adult↗
PubMed1982

Temperamental differences, family relationships, and young children's response to change within the family.

In a longitudinal study of 40 firstborn children, temperamental differences between the children were found to be linked to the emergence and persistence of anxious and unhappy behaviour over the year following the birth of a sibling. Direct observation showed that these temperamental differences were also associated with differences in the children's interactions with their mothers, and with differences in their behaviour towards their mothers when mother and sibling were interacting. In contrast, the wide range of individual differences in the behaviour of the firstborn children to their siblings was not associated with temperamental difference between the children. There was some evidence for continuity in temperamental differences between the assessments before and after the sibling birth, but in many children the behavioural changes were marked. These findings underline the clinical significance of temperamental differences in children's vulnerability to changes in family life; they also indicate that 'temperament' should be considered not as a characteristic of the child independent of his or her particular family relationships but, on the contrary, as closely linked to his or her relationship with the mother, and as susceptible to the effects of marked change in the family environment.

Birth Order↗