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Biomedical subjects

J Osborne

Publications and source records attributed to J Osborne.

At least 19 recordsLinked to original sources
PubMed1992

Nitric oxide circulates in mammalian plasma primarily as an S-nitroso adduct of serum albumin.

We have recently shown that nitric oxide or authentic endothelium-derived relaxing factor generated in a biologic system reacts in the presence of specific protein thiols to form S-nitrosoprotein derivatives that have endothelium-derived relaxing factor-like properties. The single free cysteine of serum albumin, Cys-34, is particularly reactive toward nitrogen oxides (most likely nitrosonium ion) under physiologic conditions, primarily because of its anomalously low pK; given its abundance in plasma, where it accounts for approximately 0.5 mM thiol, we hypothesized that this plasma protein serves as a reservoir for nitric oxide produced by the endothelial cell. To test this hypothesis, we developed a methodology, which involves UV photolytic cleavage of the S--NO bond before reaction with ozone for chemiluminescence detection, with which to measure free nitric oxide, S-nitrosothiols, and S-nitrosoproteins in biologic systems. We found that human plasma contains approximately 7 microM S-nitrosothiols, of which 96% are S-nitrosoproteins, 82% of which is accounted for by S-nitroso-serum albumin. By contrast, plasma levels of free nitric oxide are only in the 3-nM range. In rabbits, plasma S-nitrosothiols are present at approximately 1 microM; 60 min after administration of NG-monomethyl-L-arginine at 50 mg/ml, a selective and potent inhibitor of nitric oxide synthetases, S-nitrosothiols decreased by approximately 40% (greater than 95% of which were accounted for by S-nitrosoproteins, and approximately 80% of which was S-nitroso-serum albumin); this decrease was accompanied by a concomitant increase in mean arterial blood pressure of 22%. These data suggest that naturally produced nitric oxide circulates in plasma primarily complexed in S-nitrosothiol species, principal among which is S-nitroso-serum albumin. This abundant, relatively long-lived adduct likely serves as a reservoir with which plasma levels of highly reactive, short-lived free nitric oxide can be regulated for the maintenance of vascular tone.

Animals↗
PubMed1992

Women physicians in dual-physician relationships compared with those in other dual-career relationships.

This study compared the career and domestic responsibilities of women physicians whose domestic partners were physicians (WP-Ps) with those of women physicians whose domestic partners were not physicians (WP-NPs). In 1988 the authors surveyed 602 women physicians in a large midwestern city regarding their career and domestic roles; 390 were physicians in training (students and residents), and 212 were physicians in practice (academic medicine and private practice). Overall, 382 (63%) responded; of the 382, 247 (65%) had domestic partners; of these 247, 91 (37%) were WP-Ps and 156 (63%) were WP-NPs. The WP-Ps were found to be twice as likely as the WP-NPs to interrupt their careers to accommodate their partners' careers. The WP-Ps also assumed significantly more domestic responsibilities and worked fewer hours practicing medicine than did the WP-NPs. The 163 women physicians in training (44-48%-of the WP-Ps and 119-76%-of the WP-NPs) demonstrated a more egalitarian division of labor overall, with no significant differences between the WP-Ps and the WP-NPs. The authors recommend that longitudinal studies be undertaken to determine whether women physicians in training continue this trend as they enter the practice of medicine.

Adult↗
PubMed1991

Centrioles in the beginning of human development.

We demonstrate the presence of centrioles in fertilized human oocytes at syngamy. Single or double centrioles within centrosomes were detected by transmission electron microscopy at one pole of the first cleavage spindle in normal and dispermic embryos (25-26 hr after insemination). Sperm centrioles were also closely associated with the male pronucleus (16-20 hr after insemination) in pronuclear stage embryos. A tripolar spindle derived from a tripronuclear embryo is also demonstrated with two centrioles at one pole. The data provide evidence that human centrioles, as those in most other animals, and unlike the mouse, are paternally derived, thus supporting Boveri's classical theory. Furthermore, this study provides insights to the proposed mechanisms of aberrant cleavage patterns of dispermic human embryos.

Blastocyst↗
PubMed1991

Elevation of follicular phase inhibin and luteinizing hormone levels in mothers of dizygotic twins suggests nonovarian control of human multiple ovulation.

OBJECTIVE: To determine whether multiple ovulation in mothers of spontaneous dizygotic (DZ) twins is because of higher hypothalamic stimulation or is in response to lower serum levels of ovarian inhibin. DESIGN: Serum hormone levels were measured at five times throughout the cycle in a sample of eight mothers of DZ twins and paired controls. On day 12, ovarian ultrasonography was performed. SETTING: Blood samples were collected in participants' homes except on day 12 when they were collected at the ultrasonography clinic. PATIENTS, PARTICIPANTS: Human volunteers who had at least one set of spontaneous DZ twins were paired with controls matched for age and parity. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Serum inhibin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) levels on approximate cycle days 1,2,8,12, and 21. RESULTS: Serum inhibin levels were elevated throughout the cycle (significantly on day 1) in mothers of DZ twins. Also elevated were early follicular FSH levels, LH levels throughout the follicular phase (significantly on days 1,2, and 8), and early to midfollicular E2 (significantly on day 8) in DZ mothers, indicative overall of greater follicular activity. CONCLUSION: It is concluded (1) that the primary cause of multiple ovulation in humans is not a decrease in inhibin secretion from the ovary; (2) the increased secretion of FSH and LH may be caused by elevated secretion of, or sensitivity to gonadotropin-releasing hormone; and (3) the elevated inhibin and E2 levels are a response to increased gonadotropin release.

Female↗
PubMed1991

Excessive follicular recruitment and growth in mothers of spontaneous dizygotic twins.

We wished to establish the frequency, regularity and laterality of multiple ovulation in mothers of dizygotic (DZ) twins and controls. Subjects had regular menses and were not using oral contraceptives. Ovarian ultrasound scans were taken over a number of cycles in 21 mothers of DZ twins and 18 controls (including 13 mothers of monozygotic [MZ] twins). Multiple large follicles (greater than or equal to 12 mm diameter) were seen significantly more frequently in mothers of DZ twins (13/21 mothers, 24/77 cycles, average +/- SE follicles/cycle 1.34 +/- 0.11) than controls (2/18 mothers, 3/31 cycles, average 1.10 +/- 0.08). Both ipsilateral and contralateral multiple follicles were observed. In one case a mother of DZ twins showed multiple large follicles in 7 out of 10 cycles in which she was scanned, including both ipsi- and contralateral patterns of occurrence.

Adult↗
PubMed1991

A comparison of performance of Shepard and Sheehy collar button ventilation tubes.

This study was designed to confirm the longer in situ life of the Sheehy collar button compared with the Shepard tube and to assess the complication rates associated with the two tubes. Cases of bilateral otitis media with effusion had a Shepard tube inserted in one ear and a Sheehy contralaterally. The insertion position was allocated randomly. The patients were then assessed at three-monthly intervals for two years. In 71 per cent of those in whom at least one tube had extruded, the Sheehy remained in situ longer. The antero-inferior tube remained longer than the postero-inferior whichever type was used. There was no significant difference between complication rates, or recurrence rates of middle ear effusion after tube extrusion, for the two types. We conclude that use of a Sheehy rather than a Shepard tube carries no increased risk of complications and the patient may require further surgery less often in total.

Adolescent↗
PubMed1991

Is what you see what you get? Breast specimen handling re-visited.

Specimen radiography is already established as an essential adjunct to excisional biopsy of mammographically detected abnormalities. Two methods of specimen sectioning following the initial specimen radiograph are described. The techniques were devised to identify the lesion accurately in the specimen for subsequent pathological analysis. They have been tailored to suit the differing facilities at two Breast Screening Centres. The methods highlight the desirability of a cooperative multidisciplinary approach to the management of breast disease. They underline the importance of radiological localization of the lesion; not only for the surgeon, but also for the pathologist.

Biopsy↗
PubMed1990

Evidence by peptide mapping that the region CD4(81-92) is involved in gp120/CD4 interaction leading to HIV infection and HIV-induced syncytium formation.

Peptide fragments of the CD4 molecule were compared in their ability to 1) inhibit CD4-dependent HIV-induced cell fusion; 2) inhibit CD4-dependent HIV infection in vitro; and 3) block gp120 envelope glycoprotein binding to CD4. Peptides from the region CD4(81-92), although inactive when underivatized, were equipotent inhibitors of CD4-dependent virus infection, cell fusion, and CD4/gp120 binding when derivatized via benzylation and acetylation. Peptides of identical chemical composition, but altered sequence and derivatization pattern that blocked gp120 binding to either CD4-positive cells or solubilized CD4, also blocked infection and fusion with similar potencies. Those that did not block gp120/CD4 interaction were also inactive in HIV-1 infection and cell fusion assays. No other peptide fragments of the CD4 molecule inhibited fusion, infection, or CD4/gp120 interaction. The peptide CD4(23-56), derived from a region of CD4 implicated in binding of CD4 antibodies that neutralize HIV infection and cell fusion, had no effect on CD4-dependent cell fusion, HIV-1 infection, or CD4/gp120 binding, but did reverse OKT4A and anti-Leu 3a blockade of gp120 binding to CD4. These data provide evidence that the 81-92 region of CD4 is directly involved in gp120 binding leading to CD4-dependent HIV infection and syncytium formation. Previous observations with structural mutants of CD4 suggest that the CDR2-homologous region of CD4 is also involved, either directly or indirectly, in binding of gp120 to CD4. The CDR2- and CDR3-like domains of CD4 may both contribute to the binding of the HIV envelope necessary for HIV-1 infection and HIV-1-induced cell fusion.

Antibodies, Monoclonal↗
PubMed1989

A spectrum of skeletal anomalies associated with pulmonary agenesis: possible neural crest injuries.

Six cases of unilateral pulmonary agenesis with skeletal and other deformities have been diagnosed in our hospitals. The various pulmonary, spinal, rib and limb anomalies with their possible inter-relationships were examined and described in detail and comparison with previously reported cases was made. It became apparent that the limb abnormalities which most constantly involved hypoplasia of the phalanges of a thumb with varying metacarpal and radial anomalies, were ipsilateral to the pulmonary agenesis in all cases. The spinal deformities involved degrees of failure of segementation of T1-T3 with other vertebrae randomly involved. Rib abnormalities also varied and did not necessarily correspond to the same side as the pulmonary agenesis. The concept of the anomalies all being part of a group of neural crest injuries was then explored.

Abnormalities, Multiple↗
PubMed1989

Galactography with contrast and dye--a two stage radiological/surgical approach to serous or bloody nipple discharge.

Patients with serous or bloody nipple discharge arising from a single duct are treated by a joint radiological/surgical approach at our institution. Two galactograms are performed; the first with contrast medium alone to identify any lesion and the second, one hour prior to surgery, using both contrast and methylene blue. This defines the area for the surgeon ensuring the involved duct is removed. Several case histories are described and the galactographic technique is detailed.

Adult↗
PubMed1988

Weight gain in children following tonsillectomy.

There is much controversial evidence that children gain weight to a significant extent following tonsillectomy, usually associated with a general improvement in health. One hundred and nine consecutive children undergoing tonsillectomy in Dundee for recurrent tonsillitis had their weight recorded pre-operatively, and twelve months after surgery were re-weighed and a symptom chart completed. The results showed the patients were generally not underweight before surgery as their median weight was on the 55th. percentile. Most parents reported an improvement in their child's appetite with a reduction in the number of sore throats after surgery. Their weights following surgery had increased by an average of 20 per cent over what would normally have been expected, but this increase in weight was not confined to underweight children, but to the entire group.

Adolescent↗