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Biomedical subjects

D O'Connor

Publications and source records attributed to D O'Connor.

At least 109 records · Page 6Linked to original sources
PubMed1989

Does chromogranin a respond to short-term mild physiologic challenge?

Plasma chromogranin A, norepinephrine, epinephrine, blood pressure, and heart rate were examined in 51 unmedicated volunteers at rest, in response to postural stimulation, and in response to a mild behavioral stressor. The short-term stressors led to the expected increases in catecholamines, blood pressure, and heart rate; however, chromogranin A was not influenced by these stimuli. Chromogranin A levels were not higher in the hypertensives, nor were they correlated with any of the other physiological variables. Although chromogranin A is coreleased with catecholamines from the sympathoadrenomedullary system, it does not respond to modest short-term postural or psychological stimuli that simultaneously evoke changes in other variables relevant to the sympathetic nervous system.

Adult↗
PubMed1989

Changes in cardiac output after acute blood loss and position change in man.

Thoracic bioimpedance cardiac output (Qtbi) was measured at 1-min intervals in 27 volunteers before, during, and after withdrawing 500 ml (3.7 to 8.5 ml/kg; mean 5.8) of blood. The effects of passive leg raising (PLR) and standing on Qtbi were measured before and after blood withdrawal. Arterial oxygen saturation (SaO2), transcutaneous oxygen tension (PtcO2), mean arterial BP (MAP), and heart rate (HR) were also measured before and after blood withdrawal. Thoracic bioimpedance cardiac index (CI) decreased 18% (0.8 +/- 0.1 L/min.m2, p less than .0001) and stroke volume index (SI) decreased 22% (14.8 +/- 2.7 ml/beat.m2, p less than .0001) after blood withdrawal. HR, MAP, SaO2, and PtcO2 were not significantly different after blood withdrawal. Before blood withdrawal PLR increased CI 6.8% (0.3 +/- 0.1 L/min.m2, p less than .0001); after blood withdrawal PLR increased CI 11.1% (0.4 +/- 0.1 L/min.m2, p less than .0001). PLR can increase stroke volume and cardiac output in hypovolemic humans.

Acute Disease↗
PubMed1988

Human papillomavirus--a study of male sexual partners.

Male sexual partners of a cohort of women with genital-tract abnormalities which were associated with human papillomavirus infection were examined for evidence of infection with human papillomavirus. Of the 214 male partners who were examined, 93.5% had visible genital lesions. Of the 196 lesions that were biopsied, 72.5% showed histological evidence of infection with human papillomavirus, and only 20.4% of subjects with histological evidence of human papillomavirus were aware of a lesion. An unexpectedly high proportion (6.1%) of lesions on which a biopsy was performed, particularly those with flat, red, indurated morphology, also showed histological evidence of penile intraepithelial neoplasia. This was not significantly more common among the partners of the women with cervical intraepithelial neoplasia than it was among the partners of the women with other evidence of genital human papillomavirus infection. Penile intraepithelial neoplasia was significantly (P less than 0.001) more common among subjects with no history of non-genital warts. We conclude that the male partners of women with human papillomavirus-associated lesions are very likely to be infected with human papillomavirus, and thus may act as a significant reservoir for the reinfection of their female partners. As the awareness of human papillomavirus-associated lesions was low among the male partners, colposcopic examination and treatment of their male partners, and/or barrier contraception, may be a necessary part of the management of women who are undergoing treatment for human papillomavirus-associated genital disease.

Adult↗
PubMed1988

Immunological studies on the occurrence and properties of chromogranin A and B and secretogranin II in endocrine tumors.

We investigated a variety of endocrine tumors for the presence of chromogranins A and B and secretogranin II. These antigens were identified by one- and two-dimensional immunoblotting and in some cases by immunohistochemistry. An antigen corresponding in electrophoretic behavior to adrenal chromogranin A was present in all types of tumors, including insulinomas, oat cell carcinomas, and Merkel cell tumors of the skin. Chromogranin B had a much more limited distribution. This antigen could not be detected in parathyroid adenomas, oat cell carcinomas, or Merkel cell tumors, either by immunoblotting and immunohistochemistry. The occurrence of secretogranin II was similar to that of chromogranin B, with the exception of a positive reaction in Merkel cell tumors. In benign pheochromocytomas, all three antigens were found consistently; whereas in two of three malignant pheochromocytomas, chromogranin B was absent. Our study establishes that in most cases chromogranins and secretogranin in tumors are identical to the adrenal antigens, but that these antigens are not always stored together. Chromogranin A is the most widely distributed marker for endocrine tumors.

Adrenal Gland Neoplasms↗
PubMed1988

Acute leukemia. Learning disabilities following CNS irradiation.

Thirteen elementary school age children with acute leukemia who had received cranial irradiation with dosages between 1,800 and 4,800 rads a mean of 6.3 years earlier were evaluated for the presence of learning disorders. The authors utilized both psychometric and educational tests. The results were analyzed according to a graduated regressed standard score procedure and yielded the following diagnoses: mental retardation, two (15%); learning disability in reading and mathematics, two (15%); learning disability in mathematics, five (39%); no psychoeducational diagnosis, four (31%). Of the nine children (69%) who qualified for a specific psychoeducational diagnosis, only three were receiving any special educational services. The failure of a previous assessment of this same group of children at our center and of other research reports to uncover a similarly high incidence of neurodevelopmental pathology may be due to the specific tests employed or to the later onset of measurable difficulties in these patients.

Brain↗
PubMed1987

Amino acid alterations in a hydrophobic region of the TraT protein of R6-5 increase the outer membrane permeability of enteric bacteria.

Two insertion mutations, each introducing a new negatively charged amino acid residue into a hydrophobic region of the TraT protein coded by the F-like plasmid R6-5 caused significant alterations in outer membrane permeability of Escherichia coli and Salmonella typhimurium, so that strains carrying plasmids with either of these mutations became sensitive to hydrophobic antibiotics.

Amino Acid Sequence↗
PubMed1987

Classification of overdose/self-poisoning presentations to an accident and emergency department.

A simple classification system of overdoses presenting to a hospital emergency department is described. Five major overdose categories were developed (accidental, suicidal behavior, recreational/experimentation, compulsive use, and an indeterminate category), which were divided into 10 subcategories. A prospective survey at an inner-city hospital in Sydney classified 199 consecutive self-poisoning presentations as being due to compulsive drug use in 38% of cases; suicidal gesture as a reaction to stress, 17%; adverse reactions to recreational or experimental use, 15%; suicidal gesture to influence others, 7%; genuine accident or noncompliance with medication, 6%; genuine suicide attempt, 3%; and pseudo-overdose, 3%. The reason for the overdose was uncertain in the remainder of the cases. Additional data are also presented, including the types of drugs involved in each overdose category. Categories of overdose may be useful in psychosocial assessment for follow-up interventions, assist in research, and help reduce negative attitudes toward overdoses.

Accidents↗
PubMed1986

Congenital acute nonlymphoblastic leukemia with translocation (9;18).

Chromosome analysis is becoming an increasingly important tool in the diagnosis and treatment of childhood malignancies. This report illustrates a new translocation t(9;18) in a neonate with congenital acute nonlymphocytic leukemia, which predicted a bone marrow relapse in a normal appearing bone marrow.

Acute Disease↗
PubMed1986

The traT protein is able to normalize the phenotype of a plasmid-carried permeability mutation of Salmonella typhimurium.

The isolation of different classes of antibiotic-supersensitive outer membrane permeability mutants of Salmonella typhimurium has been described previously (Sukupolvi et al., 1984, Journal of Bacteriology 159, 704-712). One of these, the SS-A mutation, sensitizes the bacteria to gentian violet and to hydrophobic antibiotics. The phenotype of the SS-A mutant was restored to normal when a cloned fragment of the F plasmid, or the R plasmid R6-5, carrying the genes traS, T and D was introduced on a multicopy plasmid. The introduction of a plasmid carrying only the traT gene showed that this gene was sufficient to restore the phenotype. Only clones with functioning traT (irrespective of copy number) restored the normal antibiotic-resistant phenotype in the SS-A mutant. An incompatibility test using a donor strain which carried transposon Tn10 in the 60 MDa plasmid of S. typhimurium and a recipient in which Tn5 was placed close to the SS-A mutation indicated that the SS-A mutation was located in the 60 MDa virulence plasmid (previously called the cryptic plasmid) of S. typhimurium. The introduction of the large virulence plasmid carrying the SS-A mutant allele into wild-type S. typhimurium or Escherichia coli resulted in strains with a phenotype identical to that of the original SS-A mutant.

Bacterial Outer Membrane Proteins↗
PubMed1985

Progression of addiction careers in young adult solvent misusers.

Four case histories of a representative sample of young adult glue sniffers who had progressed to using illicit drugs or abusing alcohol or both contained several common factors that may have been relevant in the transition. For example, all had suffered parental deprivation or rejection in childhood leading to a state of chronic stress, and all had progressed from sniffing glue to inhaling heroin and thence to "snorting" and injecting heroin. The exact reason for the transition from glue sniffing to misusing other substances was not clear. Nevertheless, although these cases represent only a minority of glue sniffers, the problem of transition may be more common than hitherto supposed.

Adolescent↗
PubMed1985

Site-specifically modified oligodeoxyribonucleotides as templates for Escherichia coli DNA polymerase I.

Oligodeoxyribonucleotides with site-specific modifications have been used as substrates for Escherichia coli DNA polymerase I holoenzyme and Klenow fragment. Modifications included the bulky guanine-8-aminofluorene adduct and a guanine oxidation product resembling the product of photosensitized DNA oxidation. By a combination of primers and "nick-mers", conditions of single-strand-directed DNA synthesis and nick-translation could be created. Our results show that the polymerase can bypass both types of lesions. Bypass occurs on a single-stranded template but is facilitated on a nicked, double-stranded template. Only purines, with guanine more favored than adenine, are incorporated across both lesions. Hesitation during bypass could not be detected. The results indicate that site-specifically modified oligonucleotides can be sensitive probes for the action of polymerases on damaged templates. They also suggest a function for polymerase I, in its nick-translation capacity, during DNA repair and mutagenesis.

Base Sequence↗
PubMed1984

Chemotherapy as an alternative to laminectomy and radiation in the management of epidural tumor.

Nine children with neuroblastoma and five with Ewing sarcoma were found at diagnosis to have epidural extension of tumor. Five children underwent laminectomy prior to referral, with good neurologic recovery in only one. Management in the other nine children did not include laminectomy. All 14 patients were given chemotherapy without radiotherapy. Rapid regression of tumor with neurologic recovery occurred in response to chemotherapy in all patients with neurologic deficits. The responses observed in these children indicate that for chemotherapy-sensitive tumors, effective chemotherapy is a feasible alternative to laminectomy and radiation therapy in the management of epidural disease.

Adolescent↗
PubMed1984

Nonspecific esterases of leukemia cell lines: evidence for activation of myeloid-associated zymogens in HL-60 by phorbol esters.

Myeloid leukemia cell line HL-60 contains fluoride-sensitive, myeloid-associated isoenzymes of nonspecific esterase that increase in activity when cultures are treated with phorbol ester. These isoenzymes are not detectable in B-lymphoblast cell line KLM-2, either in control or in phorbol-ester-treated cultures. No increased de novo synthesis of the isoenzymes is detectable in HL-60 treated with phorbol ester. The data suggest stimulated conversion of a preformed, myeloid-associated zymogen in HL-60.

Cell Line↗
PubMed1982

The treatment of anorgasmia: long-term effectiveness of a short-term behavioral group therapy.

A long-term follow-up of 19 women who participated in short-term group therapy for anorgasmia using masturbation and assertiveness training showed that the majority of women maintained treatment gains and progressed further in orgasm response and other aspects of sexual functioning, including assertiveness and liberalness of sexual attitudes. However, several women regressed, and four additional women who dropped out of treatment also improved dramatically in orgasm response, suggesting that other patient characteristics and factors affect apparent treatment outcome. Independent evaluations, standardized assessment scales, long-term, in-person follow-ups and multidimensional assessment are useful in evaluating treatment effectiveness.

Adolescent↗