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Biomedical subjects

R Osborn

Publications and source records attributed to R Osborn.

18 recordsLinked to original sources
PubMed1992

Recovery of tracheal epithelium following high frequency ventilation at low inspired humidity.

We used scanning electron microscopy (SEM) and light microscopy (LM) to study the recovery of tracheal epithelium in newborn lambs damaged by high frequency flow interrupted ventilation (HFFIV) at low inspired humidity (30%). Newborn lambs were mechanically ventilated for 6 h, allowed to recover and subsequently killed at 2, 7 or 14 days. The recovery of the trachea above and below the tip of the endotracheal tube (ETT) was studied at these time periods and compared to a control non-intubated group and a group killed immediately after 6 h of ventilation. Above and below the ETT, SEM and LM revealed deciliation to be greatest 2 days after ventilation. The damaged tracheal mucosa had converted to non-ciliated epidermoid squamous metaplastic cells. Recovery was not complete by 14 days, although the squamous cells had already differentiated into goblet and ciliated columnar epithelial cells. No difference was seen in the rate of recovery of the tracheal mucosa above or below the tip of the ETT.

Animals↗
PubMed1991

Single-chain ribosome inactivating proteins from plants depurinate Escherichia coli 23S ribosomal RNA.

The rRNA N-glycosidase activities of the catalytically active A chains of the heterodimeric ribosome inactivating proteins (RIPs) ricin and abrin, the single-chain RIPs dianthin 30, dianthin 32, and the leaf and seed forms of pokeweed antiviral protein (PAP) were assayed on E. coli ribosomes. All of the single-chain RIPs were active on E. coli ribosomes as judged by the release of a 243 nucleotide fragment from the 3' end of 23S rRNA following aniline treatment of the RNA. In contrast, E. coli ribosomes were refractory to the A chains of ricin and abrin. The position of the modification of 23S rRNA by dianthin 32 was determined by primer extension and found to be A2660, which lies in a sequence that is highly conserved in all species.

Abrin↗
PubMed1987

Isotretinoin produces significant inhibition of monocyte and neutrophil chemotaxis in vivo in patients with cystic acne.

The effect of oral isotretinoin (13-cis-retinoic acid) on in vivo chemotactic responses was studied longitudinally in 7 patients with cystic acne. As measured in a microchamber chemotaxis assay, both monocyte and neutrophil chemotaxis were inhibited 98% (p less than 0.001) during isotretinoin treatment. In vivo chemotactic responses returned to normal within 2 months of cessation of treatment. Biopsies of skin chamber sites from patients on isotretinoin showed no significant dermal or epidermal leukocytic accumulation in response to autologous zymosan-activated serum, whereas chambers from controls showed extensive neutrophilic infiltrates even in the epidermis. In contrast, in vitro chemotactic responses of neutrophils and monocytes from patients on isotretinoin were not diminished. Sera and plasma from patients on isotretinoin contained no inhibitors of chemotaxis, and activated sera from these patients were excellent attractants for normal monocytes. We postulate that isotretinoin produces significant anti-inflammatory effects by inhibition of monocyte and neutrophil chemotaxis across intact biologic barriers in vivo.

Acne Vulgaris↗
PubMed1985

Boomerang dysplasia.

Explore the source record for details and available documents.

Abnormalities, Multiple↗
PubMed1984

Anthracycline-induced cardiomyopathy in children: a report of six cases.

Although anthracycline antibiotics are among the most useful chemotherapy agents, the risk of producing cardiomyopathy and the absence of a reliable noninvasive technique to predict subclinical cardiomyopathy remain a major problem. We retrospectively reviewed our experience with anthracyclines over a 5-year period. Cardiomyopathy developed in 6 of 112 patients (5.3%) treated with anthracyclines and was fatal in 5 of the 6 patients. Our incidence and mortality rates are higher than those previously reported.

Adolescent↗
PubMed1984

Renal tissue oxygenation following induced hypotension in dogs.

Renal oxygenation was studied during induced hypotension in mongrel dogs, anaesthetized with 1-1.5% halothane in oxygen. Hypotension was induced with an infusion i.v. of sodium nitroprusside (SNP) 70 +/- 17 micrograms kg-1 min-1 (mean +/- SEM) or trimetaphan (TMP) 36 +/- 16 micrograms kg-1 min-1, or by controlled arterial haemorrhage (45 +/- 6 ml/kg of body weight). Mean arterial pressure (MAP), cortical (Pcto2) and medullary (Pmto2) tissue oxygen tensions, arterial (Pao2), renal venous (Prvo2), and urine (Puo2) oxygen tensions were measured during the 40-min control, hypotension, and recovery periods. MAP was decreased to approximately 60% of the control value. Pcto2 decreased significantly (P less than 0.05) in all three groups while Pmto2 decreased significantly only in the haemorrhage group. Upon restoration of MAP to normal values, renal tissue oxygen tensions recovered in all groups, somewhat more rapidly in the SNP group. There were no significant differences in Pao2, Prvo2, and Puo2 during control, hypotension and recovery periods in the three groups. Tissue oxygen tension values followed the changes in MAP, but were not hypoxic, leading us to believe that both SNP and TMP are hypotensive agents safe for the kidney.

Animals↗
PubMed1981

Contraction of isolated airway smooth muscle by synthetic leukotrienes C4 and D4.

The pharmacology of leukotrienes (LT) C4 and D4 in isolated airway smooth muscle was investigated. In rat trachea, neither LTC4 or D4 elicited a response. In contrast, LTC4 was a potent contractile agonist in guinea-pig trachea, bronchus and parenchymal lung strip. Similar effects were obtained with LTD4 in trachea and parenchyma. In trachea and bronchus, the concentration-response curve to LTC4 was biphasic: indomethacin converted the biphasic response curve to a simple sigmoidal shape and enhanced the maximum contractile response. The SRS-A antagonist FPL 55712 antagonized the effect of LTD4 in both trachea and parenchyma. As regards LTC4-induced contraction of trachea and bronchus, FPL 55712, depending on concentration, either antagonized, or antagonized and enhanced the maximum contractile response. The enhancement of the maximum contractile response by FPL 55712 was not apparent when indomethacin was present. FPL 55712 failed to antagonize the effect of LTC4 in parenchyma.

Animals↗
PubMed1981

Enhancement of isolated airway responses to bronchoconstrictive agonists by the slow-reacting substance of anaphylaxis antagonist FPL 55712.

The activity of the SRS-A antagonist FPL 55712 against histamine, carbachol and ion-induced contraction of isolated airway smooth muscle was evaluated. FPL 55712 enhanced responses of guinea-pig trachea and parenchymal lung strips to histamine and carbachol. Enhancement was not obviously related to concentration. It is suggested that this effect may be the result of cyclo-oxygenase inhibition by FPL 55712. These observations may account for some of the anomalous findings regarding the antagonism of leukotrienes by FPL 55712 previously reported.

Animals↗
PubMed1976

Canine airway responses to acetylcholine, prostaglandin F2alpha, histamine, and serotonin after chronic antigen exposure.

Dose-response curves were obtained for aerosols of acetylcholine (ACh), prostaglandin F2alpha (PGF2alpha), histamine (H), and 5-hydroxytryptamine (5-HT) on pulmonary resistance (Rp) and dynamic lung compliance (Cdyn) in Ascaris-hypersensitive dogs. Previously, these animals had been subjected to chronic biweekly "allergic asthmatic" episodes by aerosol administration of Ascaris antigen. When examined either one week before or after antigen provocation the airways were not hyperreactive to ACh, H, or 5-HT but did demonstrate a modest hyperreactivity to PGF2alpha. When aerosol dose-response curves were obtained for these agonists immediately following an "allergic asthmatic" episode, the airways were hyporeactive to PGF2alpha, H, and 5-HT, but not to ACh. Studies with atropine indicated that the hyporeactivity was the result of decreased airway responsiveness to both direct and indirect effect of PGF2alpha and H. It is concluded that, in dogs, chronic antigen challenge is not accompanied by a general increase in airway reactivity to pharmacologic agents.

Acetylcholine↗
PubMed1976

Age-related immunity to measles, mumps and rubella in Middle American and United States children.

Serum samples from 3000 1 to 15-year-old children residing in the Dominican Republic, Honduras and the Republic of Panama were analyzed for measles, mumps and rubella susceptibility. These data were compared with results obtained on sera drawn from 2221 United States children of similar ages. It was found that children in all areas usually acquired immunity to measles early in life and tended to contract mumps and rubella somewhat later. Immunity data from the urban areas of the United States closely resembled that from the urban areas of the Dominican Republic. Honduran and Panamanian children showed much higher age-related frequencies of rubella, susceptibility. When compared to the other Middle American countries studied, the rural Honduran sample showed significantly higher age-grouped susceptibility rates for measles and simultaneous triple rate revealed a consistent bias, indicating that the attack rates of the three infections are not entirely independent.

Adolescent↗
PubMedDate not supplied

Expanded cytologic criteria for the diagnosis of adenocarcinoma in situ of the cervix and related lesions.

Fifty-two cases of adenocarcinoma in situ (AIS) of the cervix uteri, or lesions closely related to AIS, have been reported by this laboratory over a five-year period. Whereas this lesion has commonly been considered a rare and usually incidental histologic finding, the large majority of these cases involved glandular atypia only and were prospectively diagnosed. Comparison of the findings from this larger series with the 11 cases of AIS described by us previously has led to a shift in emphasis from cell size to sheet architecture as the primary cytologic criterion for diagnosis of this lesion. The structure of AIS sheets was consistent with respect tothe cytologic appearances described here, even when the cells were poorly preserved. Retrospective studies of Papanicolaous smears of other cases from this laboratory that were confirmed histologically as endocervical dysplasia, microinvasive or early invasive adenocarcinoma or deeply invasive adenocarcinoma indicate that these entitites can be distinguished from AIS primarily on the basis of the architecture of the sheets of cells. Cellular groups comprising small, crowded nuclei were a feature of several undercalled deeply invasive adenocarcinomas, and the diagnostic significance of this material is discussed.

Adenocarcinoma↗