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Biomedical subjects

M Simmons

Publications and source records attributed to M Simmons.

88 records · Page 5Linked to original sources

Respiratory status of Los Angeles firemen. One-month follow-up after inhalation of dense smoke.

A standardized respiratory questionnaire and detailed pulmonary function tests were administered to 21 Los Angeles firemen one month following exposure to the combustion products of polyvinylchloride, which had produced transient hypoxemia in 19 of the firemen. The results of these studies were compared with those obtained in a sample of nonfiremen residing in the Los Angeles area who were matched by computer with the firemen for anthropomorphic characteristics and smoking status. The frequency of respiratory symptoms, the results of spirometric and plethysmographic studies, and the single-breath nitrogen washout were similar in the firemen, compared with the matched sample, whereas closing volume was higher in the matched controls. These findings suggest that although fighting fires may result in acute pulmonary injury secondary to discrete episodes of inhalation of smoke, it does not appear to predispose to the development of chronic respiratory symptoms or chronic functional respiratory impairment.

Adult↗

Estrogen (E2) and glucocorticoid (Gc) effects on microglia and A beta clearance in vitro and in vivo.

The accumulation of fibrillar aggregates of beta Amyloid (A beta) in Alzheimer's Disease (AD) brain is associated with chronic brain inflammation. Although activated microglia (mu glia) can potentially clear toxic amyloid, chronic activation may lead to excessive production of neurotoxins. Recent epidemiological and clinical data have raised questions about the use of anti-inflammatory steroids (glucocorticoids, Gcs) and estrogens for treatment or prevention of AD. Since very little is known about steroid effects on mu glial interactions with amyloid, we investigated the effects of the synthetic Gc dexamethasone (DXM) and 17-beta estradiol (E2) in vitro in a murine mu glial-like N9 cell line on toxin production and intracellular A beta accumulation. To determine whether the steroid alterations of A beta uptake in vitro had relevance in vivo, we examined the effects of these steroids on A beta accumulation and mu glial responses to A beta infused into rat brain. Our in vitro data demonstrate for the first time that Gc dose-dependently enhanced mu glial A beta accumulation and support previous work showing that E2 enhances A beta uptake. Despite both steroids enhancing uptake, degradation was impeded, particularly with Gcs. Distinct differences between the two steroids were observed in their effect on toxin production and cell viability. Gc dose-dependently increased toxicity and potentiated A beta induction of nitric oxide, while E2 promoted cell viability and inhibited A beta induction of nitric oxide. The steroid enhancement of mu glial uptake and impedence of degradation observed in vitro were consistent with observations from in vivo studies. In the brains of A beta-infused rats, the mu glial staining in entorhinal cortex layer 3, not associated with A beta deposits was increased in response to A beta infusion and this effect was blocked by feeding rats prednisolone. In contrast, E2 enhanced mu glial staining in A beta-infused rats. A beta-immunoreactive (ir) deposits were quantitatively smaller, appeared denser, and were associated with robust mu glial responses. Despite the fact that steroid produced a smaller more focal deposit, total extracted A beta in cortical homogenate was elevated. Together, the in vivo and in vitro data support a role for steroids in plaque compaction. Our data are also consistent with the hypothesis that although E2 is less potent than Gc in impeding A beta degradation, long term exposure to both steroids could reduce A beta clearance and clinical utility. These data showing Gc potentiation of A beta-induced mu glial toxins may help explain the lack of epidemiological correlation for AD. The failure of both steroids to accelerate A beta degradation may explain their lack of efficacy for treatment of AD.

Amyloid beta-Peptides↗

Compatibility of etoposide phosphate with selected drugs during simulated Y-site injection.

OBJECTIVE: To evaluate the physical compatibility of etoposide phosphate with 101 selected secondary drugs, including antineoplastic chemotherapy agents, anti-infectives, and supportive care drugs, during simulated Y-site injection. DESIGN: Five-milliliter samples of etoposide 5 mg/mL as phosphate in 5% dextrose injection were mixed with 5 mL of the selected drugs diluted in 5% dextrose injection or, if necessary to avoid incompatibilities with the diluent, 0.9% sodium chloride injection. Samples were examined visually in normal fluorescent light with the unaided eye and using a Tyndall beam (high-intensity monodirectional light) to enhance the visibility of small particles and low-level haze. Turbidity of each sample was measured. In selected samples, electronic particle content assessment was performed. All of the samples were assessed initially and at one and four hours. RESULTS: Most of the secondary drugs were physically compatible with etoposide phosphate during the four-hour observation period. However, seven drug combinations had incompatibilities that included color change, increase in haze or turbidity, particulate formation, and gross precipitation. The drugs that were observed to be physically incompatible with etoposide phosphate were amphotericin B, cefepime hydrochloride, chlorpromazine hydrochloride, imipenem-cilastatin sodium, methylprednisolone sodium succinate, mitomycin, and prochlorperazine edisylate. CONCLUSION: Etoposide 5 mg/mL as phosphate in 5% dextrose injection is physically compatible for four hours at room temperature during simulated Y-site administration with 94 of the 101 drugs selected. Simultaneous Y-site administration of etoposide phosphate with the seven incompatible drugs should be avoided.

Antineoplastic Agents↗

Relative sensitivity and specificity of salivary and serum cotinine in identifying tobacco-smoking status of self-reported nonsmokers and smokers of tobacco and/or marijuana.

Serum and salivary cotinine levels were measured in 327 smoking and nonsmoking participants in a study of the health effects of marijuana with and without tobacco. These individuals had no reason to misrepresent their current tobacco-smoking status. The sensitivity, specificity, and predictive values positive and negative of the cotinine levels in distinguishing self-reported current tobacco smokers from nonsmokers was high (88-100%) and essentially the same for both fluids. Agreement between self-report and cotinine levels was not influenced by the presence or absence of marijuana smoking. A good correlation was found between serum and salivary cotinine levels in self-reported tobacco smokers (r = 0.84, p less than 0.001). Mean average levels were 279 +/- 144 ( +/- standard deviation) ng/ml for serum and 360 +/- 195 ng/ml for saliva. In a separate group of seven tobacco smokers, cotinine levels in saliva were found to be essentially independent of salivary flow rate. An analogous relationship has been observed by others for various compounds that are filtered to saliva from the blood. This may explain the close relationship observed between serum and salivary cotinine levels, and the observation made by others that the half-life of salivary cotinine is similar to that of serum cotinine.

Cotinine↗

Fetal echocardiography at West Virginia University: a seven-year experience.

The last decade has seen tremendous growth and utilization of fetal echocardiography. In order to assess the indications and yield of fetal echocardiography at West Virginia University, all fetal echocardiograms performed during a seven-year period were reviewed. There were 931 fetal echocardiograms performed on 803 women during this time period and there was a large increase in referral rate as has been seen in other regions. The highest yield of abnormalities was seen in fetuses referred secondary to the finding of an abnormal fetal cardiac exam on routine screening ultrasound (55.6%), or fetal anomalies of other organs (8.2%). These two indications alone were responsible for 77.8% of identified cases of congenital heart disease by fetal echocardiography during this time period. The resultant findings highlight the need for thorough obstetrical screening ultrasound, including the four chamber view of the heart.

Echocardiography↗

Axillary vein thrombosis during pregnancy in association with a lupus anticoagulant.

A 42-year-old multiparous pregnant woman presented with swelling and pain of the left arm at 34 weeks gestation. She had no discoloration of her arm nor a loss of radial pulse. Duplex scanning demonstrated a thrombosis in the axillary vein. She was found to have a positive circulating lupus anticoagulant. Intravenous heparin was administered and resulted in resolution of discomfort and swelling on day four of therapy. The patient was maintained on therapeutic doses of subcutaneous heparin until vaginal delivery at 39 weeks. Prenatal course was complicated by a resolving infection believed to be due to cat-scratch disease which produced a five centimeter cystic lesion in the left axillae which was removed in the first trimester. Titers for cat-scratch disease were positive for mother and infant at delivery but infant titers were negative at six weeks. Axillary vein thrombosis in pregnancy can be complicated by pulmonary embolism and should be treated by heparin.

Adult↗