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Biomedical subjects

A Johnson

Publications and source records attributed to A Johnson.

At least 559 records · Page 31Linked to original sources
PubMed1984

Enhancement of renal venous renin ratios by intravenous hydralazine in renovascular hypertension.

Renal venous renin (RVR) studies were done in 34 patients with moderate-to-severe hypertension before (unstimulated) and after (15- and 30-minute samples) a 20-mg bolus of i.v. hydralazine. The unstimulated lateralizing ratio of angiographically abnormal kidney or ipsilateral (I) to contralateral (C) RVR of greater than or equal to 1.5 was found in 69%, and the unstimulated ratio of I-inferior vena cava (IVC) renin below renal veins (I-IVC)/IVC (index of reduced renal blood flow) of greater than or equal to 0.48 was present in 50% of 16 patients (10 unilateral and 6 bilateral renal artery stenosis). The I/C and I-IVC/IVC ratios were abnormal in 100% and 88%, respectively, in 1 or both of the posthydralazine sampling in these patients. Hydralazine increased the absolute RVR from the ischemic kidney more than the contralateral kidney and did not result in new false-negative or positive I/C ratios. It is concluded that hydralazine stimulation of RVR is a safe and reliable way to determine the functionally significant pressor kidney in renovascular hypertension.

Clinical Enzyme Tests↗
PubMed1984

Uterine prolapse in the neonate.

The rare condition of neonatal uterine prolapse is usually associated with congenital spinal defects and is often resistant to simple reduction. Previously, treatment has been primarily surgical and often deforming. In this case report a silastic-ensheathed pessary fashioned from a rubber Penrose drain allowed a nonoperative, simple and permanent correction, permitting the more important, yet less obvious, associated defects to take therapeutic precedence.

Female↗
PubMed1984

Nadolol binding to human serum proteins.

Nadolol protein binding was measured in serum from 95 healthy subjects. Binding was found to range between 4 and 27%, with a mean of 14 +/- 4% (s.d.). There was a small but significant correlation found between the degree of nadolol binding and the serum alpha-1-acid glycoprotein concentration. However it was concluded that changes in the serum protein binding of nadolol were unlikely to give rise to any untoward clinical effects.

Adrenergic beta-Antagonists↗
PubMed1984

Effect of alveolar hypoxia on regional pulmonary perfusion.

We examined the effects of varying levels of alveolar hypoxia on regional distribution of pulmonary blood flow (QL) in control-ventilated sheep. Regional distribution of QL was measured using 15-micron-diam labeled microspheres during the base-line period and at two levels of hypoxemia (arterial O2 partial pressure 44 and 20 Torr). During the base-line period, regional distribution of QL in the prone position was uniform [14 +/- 4% (SE) of QL/g bloodless dry lung wt in the upper lung and 16 +/- 2% of QL/g in the dependent lung]. During hypoxemia, however, the regional distribution of QL increased in the upper lung (20 +/- 3% of QL/g) while it decreased in the dependent lung (10 +/- 2% of QL/g). The degree of flow distribution was proportional to the severity of hypoxemia. The flow distribution was not associated with significant increases in pulmonary blood flow (2.0 +/- 0.4----2.4 +/- 0.5----2.6 +/- 0.1 l/min) but was associated with increases in mean pulmonary arterial pressure (17.8 +/- 1.3----21.7 +/- 1.1----29.0 +/- 3.8 Torr). Therefore alveolar hypoxia results in a relative increase in regional pulmonary perfusion to the upper lung, which depends on the level of pulmonary hypertension. The increased upper lung perfusion may be due to recruitment in the upper lung or to vasodilation in this region.

Animals↗
PubMed1984

Alternating combination chemotherapy for stages III and IV ovarian carcinoma.

Thirty-nine previously untreated patients with stages III and IV ovarian carcinoma were treated with debulking surgery, followed by alternating combination chemotherapy with cisplatin, Adriamycin (Adria Laboratories, Columbus, Ohio), and cyclophosphamide (PAC); and hexamethylmelamine, cyclophosphamide, methotrexate, and 5-fluorouracil (HexaCAF). Of 19 patients with measureable disease at the onset of therapy, ten (53%) had at least a partial response to chemotherapy. Seven (18% of total) patients were found to be pathologically free of disease at secondlook surgery, but four patients relapsed 19 to 31 months after initiating therapy. The median progression-free survival period of all 39 patients entered into the study is 12 months, and the median crude survival is 21 months. The PAC/HexaCAF alternating combination chemotherapy regimen may be administered with moderate toxicity, but the treatment results are not superior to those reported for PAC or HexaCAF alone in advanced ovarian carcinoma.

Adenocarcinoma↗
PubMed1984

1984 Hodge memorial Award--surface wrinkles, cell ridges, and desquamation in the external auditory canal.

The phenomenon of epithelial migration from the tympanic membrane laterally along the external auditory meatus has long been recognized, and the site of keratin desquamation observed. In this study, the surface features of deep canal epithelium have been studied in 14 human temporal bones, and skin removed from 21 human temporal bones has been sectioned and studied by light microscopy. The findings reveal the role of hairs and ceruminous glands in the desquamation of deep canal stratum corneum, and elucidate the migratory mechanism. The formation an distribution of keratin wrinkles and cellular ridges in the external canal are explained.

Adult↗
PubMed1984

Mast cells in human middle ear mucosa in health and in disease.

The distribution of mast cells was studied in normal human middle ear mucoperiosteal lining and in middle ear biopsies of patients with acute and chronic otitis media. The mast cells were identified on the basis of the metachromatic staining for their cytoplasmic granules with Giemsa and toluidine blue. Only a few mast cells located in proximity to blood vessels in the lamina propria underneath the epithelial layer were observed in normal middle ear mucoperiosteum. The number of mast cells in acute inflammatory reactions and in the normal middle ear lining was similar. By contrast, the mast cell count was significantly increased in chronic inflammatory reactions. The population density of the mast cells was the highest in the subepithelial layer of cholesteatoma, in regions where the lamina propria showed fibrosis and infiltration with chronic inflammatory cells, and around mucous glands. The presence of increased numbers of mast cells in chronic otitis media is consistent with our previous finding of high levels of histamine in middle ear effusions. It is postulated that mast cells play an important role in the pathogenesis of chronic otitis media through the release of their active biochemical mediators.

Adolescent↗
PubMed1984

Differential effects of complement activation induced by cobra venom factor on pulmonary transvascular fluid and protein exchange.

Sheep were prepared with lung lymph fistulas for assessment of the effects of complement activation on pulmonary transvascular fluid and protein exchange in the intact animal. Cobra venom factor (CVF 200 +/- 46 U/kg) was injected intravenously for activation of the complement system. In some animals (n = 6), pulmonary lymph flow (Qlym) and pulmonary arterial pressure (Ppa) increased without a change in the lymph-to-plasma protein concentration ratio (L/P) or in pulmonary blood flow (QL), indicating an increase in pulmonary vascular permeability to proteins. In another group (n = 6), Qlym and the L/P did not change, and there were also no changes in Ppa and QL following a similar injection of CVF. Morphologic evidence showed that leukocytes were trapped in pulmonary vessels and interstitium of both groups. Pulmonary edema was also present in both groups. Complement activation does not uniformly increase pulmonary lymph flow despite pathologic evidence of leukocyte sequestration and pulmonary edema. The lack of change in lymph flow in some animals may be due to lymphatic insufficiency, or lack of generation of humoral mediators, and/or a decrease in pulmonary capillary pressure.

Animals↗
PubMed1983

Anti-inflammatory agents III: Structure-activity relationships of brusatol and related quassinoids.

A series of quassinoids were observed to be potent inhibitors of induced inflammation and arthritis in rodents. Brusatol afforded the most potent activity followed by brucein-D. A 3-hydroxy-delta 3-2-oxo moiety in brusatol or a 1-hydroxy-delta 3-2-oxo moiety in brucein-D, as well as a C-15 ester-bearing delta-lactone ring in brusatol and C-11 and C-12 free hydroxyl groups are required in both quassinoids for potent anti-inflammatory activity. Preliminary studies indicate that one of the modes of action of quassinoids as anti-inflammatory agents is to stabilize lysosomal membranes, reducing the release of hydrolytic enzymes that cause damage to surrounding tissues.

Animals↗
PubMed1983

Half-lives and relative amounts of stored and polysomal ribosomes and poly(A) + RNA in mouse oocytes.

Growing mouse oocytes were labeled in vitro with [3H]uridine and chased for 2 or for 7 days to estimate the relative amounts of RNA appearing in different fractions and to follow their turnover. Oocytes were lysed and thoroughly dispersed in the presence of 1% DOC, and centrifuged on sucrose gradients to separate polysomes from smaller components not engaged in translation. After the short chase, one-third of the labeled ribosomes appeared in EDTA-sensitive polysomes. The proportion of ribosomes in both fractions remained stable during the long chase, demonstrating no net flow from one fraction to the other. When gradient fractions were analyzed by poly(U) Sepharose chromatography, it was found that about 20% of the labeled poly(A)+ RNA appeared in polysomes after the short chase. The half-lives of stored and translated mRNA were followed relative to stable rRNA during the long chase. Stored mRNA was completely stable, but translated mRNA turned over with a t1/2 of about 6 days. Other methods for separating stored from translated components were not successful, including sedimentation of putative large complexes (fibrillar lattices) containing stored components, or chromatography of lysates on oligo(dT)-cellulose. Results presented here combined with our previous results demonstrate that, during meiotic maturation, the percent of labeled stable RNA which is polyadenylated declines from 19 to 10%, suggesting deadenylation or degradation of half of the accumulated maternal mRNA.

Animals↗
PubMed1983

Spontaneous forebrain neuronal activity in developmentally protein malnourished rats.

The characteristics of the spontaneous discharges of populations of single neurons in the neocortex and thalamus of rats reared under chronic protein malnutrition (8% casein) or a normal diet (25% casein) were evaluated. Results from 700 neurons showed the malnourished rats had fewer fast firing cells, an overall lower discharge rate and an altered firing pattern (fewer cells which exhibited bursting activity). These findings are the first demonstration of altered neuronal discharges in the forebrains of adult malnourished rats.

Action Potentials↗
PubMed1983

Oral antibiotic prophylaxis in patients with cancer: a double-blind randomized placebo-controlled trial.

In an attempt to reduce the incidence of fever and infection, we randomized patients with cancer to receive trimethoprim/sulfamethoxazole plus erythromycin (TMP/SMX + E) versus placebos after each cycle of chemotherapy (no crossover) and to continue until granulocytopenia (polymorphonuclear leukocytes less than 500/mm3) resolved or the patient became febrile. We evaluated 541 episodes (150 patients); 249 episodes (77 patients) with TMP/SMX + E and 292 episodes (73 patients) with placebos. The patients' median age was 17 years. Thirty percent of the patients had leukemia, 23% had lymphoma, and 47% had solid tumors. Compliance with prescribed medication was prospectively rated as excellent in 60.6%, good in 11.7%, poor in 11.1%, and unknown in 16.6%; compliance was better for the placebo group (P = 0.001). The overall incidence of fever or infection was 22.1% for the TMP/SMX + E group versus 26.9% for the placebo group. When only episodes with excellent compliance in which granulocytopenia was documented were compared, the incidence of fever or infection was 18.1% for the TMP/SMX + E group vs 32.2% for the placebo group (P = 0.009), with bacterial infection occurring in 3.8% of the TMP/SMX + E group vs 11.9% of the placebo group (P = 0.019), and unexplained fever in 10.5% of the TMP/SMX + E group vs 19.6% of the placebo group (P = 0.037). Patients with good or poor compliance showed no significant benefit from the TMP/SMX + E, and patients with excellent compliance did best, regardless of whether they were receiving antibiotics or placebos, suggesting that patient compliance is an important independent variable. The incidence of fever or infection was significantly lower for patients with leukemia with excellent compliance who received antibiotics (P = 0.037) than for patients with lymphomas or solid tumors. Oral antibiotic prophylaxis reduced the incidence of fever and infection in some granulocytopenic patients, but the benefit was limited and restricted to patients whose compliance was complete.

Adolescent↗
PubMed1983

Portable emergency ventilators. A lung model study.

The ventilatory performance of four portable emergency ventilators (Logic 07, Motivus, Oxylog and Pneupac II) was tested on a lung model. The model consisted of one common (tracheal) tube, two separate (bronchial) tubes in which different obstructions could be applied, and two glass jars filled with water to suitable compliances. Dialled volume was compared to measured volume. The gas distribution produced by the different ventilators was also studied. It was found that all four ventilators could distribute gas to the lungs. The ventilators Logic 07 and Oxylog had acceptable relationships between dialled and measured volume/frequency and they also produced a good final distribution.

Airway Obstruction↗