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Biomedical subjects

D Rosenberg

Publications and source records attributed to D Rosenberg.

At least 19 recordsLinked to original sources
PubMed1992

Airway responsiveness in infants following bronchiolitis.

Airway responsiveness to inhaled methacholine was assessed in 18 infants, 4 and 10 months old, following bronchiolitis. Pulmonary function was measured from partial expiratory flow-volume curves generated by the rapid compression technique. Sleeping infants inhaled increasing concentrations of methacholine until maximal expiratory flows at functional residual capacity (VmaxFRC) decreased by 30% or 2.5 mg/mL was inhaled. Airway responsiveness was quantitated by: 1) the threshold concentration (log TC) required to decrease VmaxFRC by 2 standard deviations from baseline; 2) the concentration required to decrease VmaxFRC by 30% (log PC30); and 3) the slope of the dose-response curve between TC and PC30 (log SPC30). At both the first and second evaluation, the bronchiolitic infants had lower baseline VmaxFRC (% pred.) than 24 control infants. In addition, the bronchiolitic infants had heightened airway responsiveness compared to controls, demonstrating lower values for logTC and logPC30 and steeper slopes to their dose-response curves (logSPC30). After accounting for the relationship between airway responsiveness and age, the occurrence of bronchiolitis was found to be a significant independent factor 10 months but not 4 months following bronchiolitis. The bronchiolitic infants did not demonstrate the decline in airway responsiveness with increasing age that occurs in normal infants. We conclude that infants exhibit heightened airway responsiveness following bronchiolitis.

Acute Disease↗
PubMed1992

Improving pregnancy outcomes: public versus private care for urban, low-income women.

This study describes the characteristics of women who received maternity care from the Chicago Department of Health or from private practitioners in 1988 and the first half of 1989, and who delivered at the University of Illinois Hospital or Cook County Hospital. The risk of preterm low birthweight for the infants of these women was compared according to source of prenatal care. The likelihood of giving birth to a preterm, low-birthweight infant was significantly greater (odds ratio 3.1, 95% confidence interval 2.3-4.0) for women who received care only from private physicians (n = 530) compared with those who received care entirely from the Chicago Department of Health (n = 2465). This relationship remained after adjustment for race, age, parity, history of adverse pregnancy outcomes, smoking, and use of drugs during pregnancy. We examined alternative explanations for these findings, and concluded that although the role of urban public health departments in the direct delivery of maternity care services continues to be a source of controversy, these institutions remain an important provider of such care for low-income women.

Chicago↗
PubMed1991

Comparison of titanium-mesh and porous disc electrodes for epicardial defibrillation.

The object of this study was to compare the effectiveness of chronically implanted porous electrodes with that of smooth mesh titanium electrodes of the same diameter but smaller effective surface area. The criteria used in evaluating the electrodes were (1) acute, subacute, and chronic resistance and (2) acute, subacute, and chronic defibrillation thresholds. Electrode pairs 2.5 cm in diameter were implanted in each of 17 dogs (ten mesh and seven porous). One electrode of each pair was sutured to the right ventricle and one to the left ventricle near the cardiac apex. Defibrillation threshold energy and total resistance were measured at the time of implantation and again 6 and 12 weeks after implantation. The mean initial resistance of the titanium electrodes was 131.7 omega; the mean defibrillation values for the porous electrode implant were 96.9 omega and 7.5 joules, respectively. Three to 6 weeks after implantation, the values for the titanium mesh electrode were 88.9 omega and 12.0 joules, while those for the porous electrode were 59.9 omega and 8.0 joules. In the chronic state, the figures for the titanium mesh electrode were 78.1 omega and 13.0 joules, while those for the porous electrode were 64.3 omega and 8.3 joules. We conclude that defibrillation can be achieved successfully with small epicardial electrodes. The findings suggest that a porous electrode, with its larger effective surface area, has lower electrode/tissue interface resistance in the acute and chronic phases, and, therefore, provides lower defibrillation threshold energy.

Animals↗
PubMed1991

Inactivation of fusidic acid by resistant Streptomyces strains.

Streptomyces lividans and several other Streptomyces species are resistant to the steroid-like antibiotic fusidic acid. This resistance is mediated by structural modification of the antibiotic. Using TLC, CD, UV, IR, NMR and mass spectroscopy the structure of one of the resulting inactive compounds was determined. It is derived from fusidic acid by the loss of an acetyl group and the formation of a lactone ring between C-21 and C-16. In addition, helvolic acid, a compound closely related to fusidic acid, has been shown to be modified.

Chromatography, Thin Layer↗
PubMed1991

Regional perinatal care in crisis: a case study of an urban public hospital.

Regionalized perinatal care is intended to guarantee pregnant women and neonates access to appropriate care regardless of ability to pay. Its effectiveness depends on the willingness of hospitals to transfer high-risk patients according to established protocols and affiliations. This study examines maternal transfers (n = 896) to Cook County Hospital (CCH), a public facility and a designated perinatal center in Chicago. In 1987 and 1988, the majority (68%) of maternal transfers to CCH came from out-of-network hospitals, and 52% of these came directly from another perinatal center. The data indicate that 62% of the out-of-network transfers who delivered were medically high-risk. The study also documents the transfer of women in active labor, a violation of federal law. The term "perinatal dumping" is introduced to mean the transfer of high-risk pregnant women between hospitals for economic rather than medical reasons. Strategies for safeguarding the integrity of regionalized perinatal care are discussed.

Adolescent↗
PubMed1990

Phenylpropanolamine and caffeine use among diet center clients.

We surveyed phenylpropanolamine (PPA) use and overuse among 309 diet center clients. Fifty-one percent of all subjects surveyed reported using PPA drugs: 44 percent used cold medicines and 16 percent used diet aids. Twenty-two percent of diet aid users and 7 percent of cold medicine users reported that they deliberately used more than the dosage recommended to improve efficacy. Among diet aid users, 59 percent also regularly consumed caffeine. Despite package warnings, individuals who had been told by their doctors that they were hypertensive used PPA products as often as normotensive individuals. PPA, the fifth most frequently used drug in the USA, is contained in over-the-counter (OTC) diet aids as well as OTC and prescription cold medicines. Severe adverse drug reactions (ADRs) including hypertensive crisis, stroke and death have been attributed to PPA products. Clinical studies have shown that using greater than recommended doses of PPA and using PPA in combination with caffeine may increase the risk of ADRs. Overweight patients may be particularly at risk for ADRs to PPA because they are likely to be hypertensive and to use diet aids. We recommend informing diet center clients of the potential dangers of consuming PPA products, especially more than the recommended dose, in the presence of hypertension, and when other sympathomimetic drugs are being taken.

Adult↗
PubMed1979

Mechanism of action of colchicine in acute urate crystal-induced arthritis.

Phagocytosis of urate crystals by human or rabbit neutrophils induces the synthesis and release of a glycoprotein, the crystal-induced chemotactic factor (CCF), which is chemotactically active both in vitro and in vivo. It has been proposed that CCF is a prime mediator of the acute gouty attack. Colchicine has been shown to decrease the production and release of this factor in vitro. In these studies, colchicine, at nonleukopenic doses, is shown to abrogate the acute arthritis induced by monosodium urate crystals in rabbits, but to have no effect upon the arthritis induced by the injection of the purified cell-derived chemotactic factor. Serum colchicine levels were 0.48-0.58 muM at 30 min and 0.12-0.3 muM at 90 min after intravenous injection of 0.2 mg/kg colchicine. Peripheral blood polymorphonuclear leukocytes obtained from colchicine-treated animals migrated normally towards a chemotactic stimulus but failed to produce CCF after phagocytosis of monosodium urate crystals. The dialyzed synovial fluid from rabbits injected with microcrystalline sodium urate contained chemotactic activity that was not present when animals were also given intravenous colchicine or injected intra-articularly with the chemotactic factor formyl-methionyl-leucyl-phenylalanine. Furthermore, the synovial fluid from rabbits injected with microcrystalline sodium urate significantly decreased (125)I-CCF binding to neutrophils. The binding of (125)I-CCF to its neutrophil receptor was not significantly reduced by the synovial fluid of colchicine-treated rabbits nor by the synovial fluid of control rabbits injected with the chemotactic factor formyl-methionyl-leucyl-phenylalanine. Colchicine (10 and 0.1 muM) was shown to have no effect upon the binding of (125)I-CCF to its cell receptor.

Animals↗
PubMed1977

A mechanism of action for non-steroidal anti-inflammatory agents in calcium pyrophosphate dihydrate (CPPD) crystal induced arthritis.

The acute inflammatory response to calcium pyrophosphate dihydrate crystals follows the meeting of neutrophils and crystals. The ensuing phagocytosis leads to the generation of a glycoprotein chemotactically active for neutrophils and to the release of lysosomal enzymes. Indomethacin and phenylbutazone, at therapeutic concentrations, impaired phagocytosis of the crystals and generation of chemotactic factor activity. Colchicine had no effect upon phagocytosis but significantly impaired the appearance of chemotactic factor activity.

Arthritis↗
PubMed1977

Induction of arthritis by purified cell-derived chemotactic factor: role of chemotaxis and vascular permeability.

The injection of monosidium urate-induced chemotactic factor into the joint cavities of rabbits induces an acute inflammatory response that resembles the one produced by monosodium urate crystals. The leukocyte accumulation induced by the factor was not accompanied by a measurable increase in vascular permeability as measured by appearance of 125I-albumin in the joint cavity. When histamine was injected into the joints, a marked increase in vascular permeability but no leukocytosis above control levels was observed. The above results suggest that the cell-derived factor is primarily responsible for the accumulation of cells seen in the acute inflammation induced by monosodium urate crystals.

Animals↗