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Biomedical subjects

R Maxwell

Publications and source records attributed to R Maxwell.

At least 55 records · Page 3Linked to original sources
PubMed1988

PaO2 increases with coughing in patients with chronic lung disease.

We considered if the cyanosis frequently observed during a cough attack in patients with chronic lung disease was due to worsening hypoxemia. To investigate the effects of cough on PaO2, we measured arterial blood gases before and after a voluntary coughing period of 45 sec, in 11 patients with Interstitial Lung Disease (ILD) and 14 patients with Chronic Obstructive Lung Disease (COPD). All patients significantly increased (p less than 0.05) their PaO2 (COPD: from 49 +/- 2 to 60 +/- 2 mmHg; ILD from 44 +/- 2 to 51 +/- 3 mmHg, mean +/- SD) and decreased their PaCO2. We conclude that stable patients with COPD and ILD increase their PaO2 with coughing most likely due to hyperventilation. The cyanosis observed could be due to peripheral circulatory effects of coughing.

Adult↗
PubMed1987

Ultrafiltration to reject human interleukin-1-inducing substances derived from bacterial cultures.

Interleukin-1 (IL-1), a polypeptide cytokine, is an important mediator of host responses to infection and injury. Picogram per milliliter concentrations of bacterial products (endo- or exotoxins) stimulate human monocytes to produce IL-1 in vitro. The design of this study was based on the clinical model of bacterial contamination of fluid intended to be directly injected into humans. Physiologic saline contaminated with bacterial toxins was passed through a hollow fiber ultrafilter, and the ultrafiltrates were tested for their ability to induce human IL-1 production. The ultrafiltrates were added directly to freshly obtained human blood mononuclear cells, and after 24 h of incubation the supernatant media were assayed for the presence of IL-1. The results indicate that the IL-1-inducing material(s) present in bacterial cultures of gram-negative organisms is rejected by a factor of 100 to 100,000 by molecular size exclusion and by absorption; rejection is sustained for at least 32 liters of fluid; the rejection of Limulus-reactive material by the ultrafilter is greater for purified endotoxin than for native endotoxins derived from live bacterial cultures; and nonendotoxin IL-1-inducing toxins (molecular weight, 24,000) from Staphylococcus aureus are not rejected or absorbed. These results demonstrate that there is a considerable margin of safety with the ultrafiltration method and that it can be applied to clinical situations.

Bacterial Toxins↗
PubMed1986

Magnetic resonance imaging, electroencephalogram, and selected neuropsychological testing in staged corpus callosotomy.

A 21-year-old man with medically intractable secondarily generalized atonic seizures underwent a corpus callosotomy on Nov 5, 1981. Though improved, the falling seizures persisted. In January 1984, magnetic resonance imaging (MRI) documented that the anterior quarter of the corpus callosum remained intact. In March, the patient underwent a completion of the callosotomy, at which time the MRI findings were corroborated. Since the second surgery, a further improvement in seizure control has been observed. Use of MRI can document both noninvasively and in vivo the extent of corpus callosotomy. The implications of selected neurophysiologic and neuropsychological findings are also discussed.

Adult↗
PubMed1986

Energy metabolism in rat pituitary tumors during stimulation of prolactin by vasoactive intestinal polypeptide and thyrotropin-releasing hormone: a study with nuclear magnetic resonance spectroscopy.

The effect of the peptides TRH and vasoactive intestinal polypeptide (VIP) on phosphate-bound energy of GH3 tumor cells in vivo was investigated using the noninvasive technique of topical 31P-nuclear magnetic resonance spectroscopy. VIP (4.0 micrograms/100 g BW) caused a reduction in the high energy metabolite phosphocreatine and an increase in inorganic phosphate. In the same experiments (n = 9), VIP stimulated PRL secretion to a value of 146% +/- 13 of basal concentrations. The change in the inorganic phosphate-phosphocreatinine ratio had a positive correlation with the increase in PRL secretion (P less than 0.001), indicating a VIP-induced energy consumption for a process related to PRL secretion. In separate experiments, in vitro, it was confirmed that VIP increased energy consumption by demonstrating an increase in glycogenolysis by the pituitary tumor cells. TRH also increased PRL secretion to 145% +/- 23 of basal values but, in contrast, did not induce changes in energy metabolites detectable by nuclear magnetic resonance. It is concluded that VIP and TRH promote PRL release through different stages in the secretion process.

Adenine Nucleotides↗
PubMed1983

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Accreditation↗
PubMed1980

Immunology of histoplasmosis: humoral and cellular activity from a polysaccharide-protein complex and its deproteinized fraction in experimentally immunized mice.

In a previous publication it was reported that a polysaccharide-protein complex (PPC), sensitive to beta-glucosidase, was isolated from Histoplasma capsulatum. This complex was strongly reactive in an agar gel diffusion assay with sera from patients with histoplasmosis, but was unreactive with sera from patients with coccidioidomycosis. Here, the studies with human sera have been expanded and attempts were made to determine the response of mice immunized with nonviable H. capsulatum or Coccidioides immitis to PPC or its deproteinized fraction (D-PPC) using more sensitive tests for antibody and including also test for cell-mediated immunity. Histoplasmin and coccidioidin were compared with PPC or its deproteinized fraction (D-PPC) in all assays. In a counterimmunoelectrophoresis (CIE) assay, PPC and D-PPC reacted only with sera from patients with histoplasmosis, whereas cross reactions were noted with histoplasmin and coccidioidin using heterologous sera. Cross-reaction were observed with all four antigen preparatins and both types of antisera using a microcomplement fixation assay. The assay for macrophage migration inhibitory factor (MIF) was also relatively nonspecific, in that inhibition occurred with cells from animals sensitized with Histoplasma or Coccidioides using both homologous and heterologous antigens. In the footpad assay, histoplasmin and coccidioidin were highly cross-reactive in animals sensitized with the heterologous fungus, but the PPC and D-PPC from H. capsulatum elicited significant reactions only in animals sensitized with Histoplasma.

Animals↗
PubMed1979

Keratoplasty and intraocular lenses: current status.

Present methods of treating combined corneal disease and cataracts in elderly patients are unsatisfactory, and multiple operative procedures may be required. From 1975 through 1978, 60 attempts were made to restore relatively normal optics and achieve rapid visual recovery with a single operative procedure consisting of keratoplasty, cataract extraction, and intraocular lens insertion in various combinations. As of this writing, there have been few complications, and 82% of the grafts are clear.

Aged↗
PubMed1977

Fasting hyperglycaemia and relatively unimpaired meal responses in mild diabetes.

Plasma glucose, insulin and triglyceride changes in response to a standard breakfast and an oral glucose tolerance test have been studied in normal, obese and diabetic subjects. Mild diabetics with an abnormal oral glucose tolerance test may have normal or near-normal incremental glucose responses to a standard breakfast. A raised fasting plasma glucose is the predominant day-to-day glucose abnormality of mild diabetes. Diabetics have decreased insulin responses to oral glucose compared with the meal, and the deficient insulin response to glucose probably accounts for both the raised fasting plasma glucose levels and the abnormal oral GTT. The initial insulin response to a meal is normal in mild diabetics, and is probably stimulated by secretogogues other than glucose. The oral glucose tolerance test is apposite for the diagnosis of diabetes in view of the impaired insulin response to glucose, but accurate measurement of the basal plasma glucose may be of equal value. The diabetic and obese subjects had normal triglyceride levels, and there was no detectable impairment of disposal of the exogenous triglyceride following the breakfast.

Aged↗