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Biomedical subjects

R E Brown

Publications and source records attributed to R E Brown.

At least 19 recordsLinked to original sources
PubMed1992

Spontaneous transfer of ganglioside GM1 from its micelles to lipid vesicles of differing size.

The spontaneous incorporation of II3-N-acetylneuraminosylgangliotetraosylceramide (GM1) from its micelles into phospholipid bilayer vesicles has been investigated to determine whether curvature-induced changes in membrane lipid packing influence ganglioside uptake. Use of conventional liquid chromatography in conjunction with technically-improved molecular sieve gels permits ganglioside micelles to be separated from phospholipid vesicles of different average size including vesicles with diameters smaller than 40 nm and, thus, allows detailed study of native ganglioside GM1 incorporation into model membranes under conditions where complicating processes like fusion are readily detected if present. At 45 degrees C, the spontaneous transfer rate of GM1 from its micelles to small unilamellar vesicles (SUVs) comprised of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) is at least 3-fold faster than that to similar composition large unilamellar vesicles (LUVs) prepared by octyl glucoside dialysis. Careful analysis of ganglioside GM1 distribution among vesicle populations of differing average size reveals that GM1 preferentially incorporates into the smaller vesicles of certain populations. This behavior is observed in SUVs as well as in LUV-SUV mixtures and actually serves as a sensitive indicator for the presence of trace quantities of SUVs in various LUV preparations. Analysis of the results shows that both differences in the diffusional collision frequency between GM1 monomers and either SUVs or LUVs and curvature-induced changes in the interfacial lipid packing in either SUVs or LUVs can dramatically influence spontaneous ganglioside uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, Liquid↗
PubMed1992

Simplified derivatization for determining sphingolipid fatty acyl composition by gas chromatography-mass spectrometry.

A simple procedure for simultaneously derivatizing non-hydroxy and hydroxy fatty acids prior to GC analysis [I. Ciucanu and F. Kerek, J. Chromatogr., 284 (1984) 179] has been evaluated for its usefulness in determining sphingolipid acyl composition. The method uses methyl iodide in polar aprotic solvents to generate methyl esters of carboxyl groups and methyl ethers of hydroxyl groups. Methylation efficiency is examined as a function of hydroxyl group presence and location in free fatty acids as well as a function of 2-hydroxy fatty acid chain length. Conditions are also reported for efficient saponification and derivatization of sphingolipid fatty acyl chains as is illustrated using bovine brain galactosylceramide.

Animals↗
PubMed1992

Rats can discriminate between the urine odors of genetically identical mice maintained on different diets.

Male Long-Evans hooded rats were tested in a habituation-dishabituation procedure for their ability to discriminate between the urine odors of male C57BL/6J mice maintained on two different diets. There were discriminable differences between the urinary odors of two individual mice maintained on different diets. The rats did not dishabituate when presented with urine odors from two individuals on the same diet or two odor samples from the same individual. These results indicate that individual urinary odors of genetically identical mice are influenced by diet. We discuss the hypothesis that diet may act together with genetic differences, commensal bacteria, and hormonal changes to convey olfactory information used for individual recognition.

Animals↗
PubMed1992

Evaluation and management of upper extremity neuropathies in Charcot-Marie-Tooth disease.

The evaluation and treatment of five patients with upper extremity neuropathies secondary to Charcot-Marie-Tooth disease were reviewed with emphasis on age at onset of Charcot-Marie-Tooth disease and upper extremity deformities, clinical findings, signs of associated nerve compression, and outcome of surgical treatment. The onset of the disease generally occurred in the first or second decade of life. The onset of upper extremity symptoms lagged behind by an average of 8 years. All patients had intrinsic minus hands with decreased sensibility. Three of five patients had clinical or electrophysiologic evidence of associated nerve compression syndromes. Treatment with standard tendon transfers, nerve compression releases, soft tissue releases, and joint fusions resulted in subjectively improved function in three of four patients undergoing reconstruction. Release of six compression neuropathies in one patient provided excellent pain relief, but the underlying neuropathy progressed. Pessimism regarding reconstructive surgery in the patient with upper extremity neuropathies secondary to Charcot-Marie-Tooth disease is unwarranted.

Adult↗
PubMed1992

Microvascular anastomosis of a rectus abdominis free flap into a prosthetic vascular bypass graft.

Distal bypass grafts are frequently employed to revascularize lower extremities and to replace major peripheral vessels following excision of large soft-tissue or bone tumors. Autogenous vein grafts are generally used for such bypasses, when available. Large wounds associated with peripheral vascular disease or excision of massive tumors frequently require concomitant free-tissue transfers. Anastomosis of a free-tissue transfer pedicle to a vein bypass graft has been reported. The first successful case of an anastomosis of a flap pedicle to a Gore-tex bypass graft is presented.

Abdominal Muscles↗
PubMed1992

Trenbolone acetate/estradiol combinations in feedlot steers: dose-response and implant carrier effects.

Two experiments were conducted at three locations to determine the correct dosage and carrier for trenbolone acetate (TBA) and estradiol (E2) implants in feedlot steers. In the dose-response experiment, 1,296 steers were allotted to six implant treatments (48 pens per location): control, 140 mg of TBA (140/0), 30 mg of E2 (0/30), 20 mg of TBA + 4 mg of E2(20/4), 80 mg of TBA + 16 mg of E2(80/16), and 140 mg of TBA + 28 mg of E2 (140/28). In the carrier experiment, 575 steers were allotted to five implant treatments (25 pens per location): control, 140 mg of TBA + 28 mg of E2 in lactose (140/28-LA), 140 mg of TBA + 28 mg of E2 in cholesterol (140/28-CH), 140 mg of TBA + 20 mg of E2 in LA (140/20-LA), and 200 mg of progesterone + 20 mg of E2 benzoate (SS, reimplanted). In both experiments steers were fed a finishing diet for 140 to 168 d. In the dose-response experiment, response to TBA alone (140/0) did not differ from control (P greater than .2). Estradiol alone (0/30) improved ADG by 7% (P less than .01) and tended to improve feed efficiency over control (3%, P = .17). The highest dosage (140/28) improved ADG by 18% (P less than .001) and feed efficiency by 10% (P less than .001) over control and 10% (P less than .001) and 7% (P less than .01) over E2 alone, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1992

Early language and communicative abilities of children with periventricular leukomalacia.

Ten 2-year-old children with periventricular leukomalacia (PVL), a brain injury associated with prematurity, were evaluated using language samples. Five children scored less than 80 on cognitive testing (delayed). Five children with this disorder and normal cognitive scores were assessed at two ages, matched with the delayed group on CA and developmental level. The delayed group produced significantly fewer lexical tokens and spontaneous verbal utterances than did the CA-matched group. No significant differences were observed between the delayed group and either comparison group on other measures of lexicon, grammar, or communication. The data demonstrate a relation between cognitive abilities and measures of verbal productivity in children with PVL.

Child↗
PubMed1992

Osteoid osteoma of the distal phalanx of the finger: a diagnostic challenge.

Osteoid osteomas of the distal phalanx of fingers are uncommon. An extensive review of the literature indicates that the diagnosis of osteoid osteoma of the distal phalanx is often delayed for several months to years (average 34.3 months). Pain is the most common finding (92 percent), followed by swelling and clubbing (75 percent). Relief of pain by aspirin was indicated in 10 patients (42 percent). Multiple operations were done in 7 patients prior to the appropriate diagnosis and treatment. A typical case report is presented to illustrate the difficulties in diagnosis and treatment of this benign bone tumor. A better awareness of this tumor may prevent unwanted delays in diagnosis and unnecessary operations.

Adult↗
PubMed1992

Efficacy of the FEF colorimetric end-tidal carbon dioxide detector in children.

Direct laryngoscopy and observation of endotracheal tube (ETT) passage between the vocal cords remain the criterion standard for verifying endotracheal intubation. Detection of end-tidal carbon dioxide (ETCO2) serves as an invaluable adjunct to confirm endotracheal intubation, detect inadvertent esophageal intubation, and monitor for accidental tracheal extubation. Capnography, however, is often unavailable outside the operating suite. A commercially available, disposable, colorimetric ETCO2 detector (FEF, Fenem, Inc., New York, N.Y.), in which color changes using a numerical scale semiquantitatively measure percent carbon dioxide in exhaled gases, has proved effective in confirming endotracheal intubation in adults, but has not been thoroughly investigated in children. We studied 20 otherwise healthy children, aged 6 mo to 8 yr, with simultaneous infrared and colorimetric ETCO2 measurements during elective general anesthesia to evaluate the efficacy of the colorimetric detector. Two hundred of 200 tracheally intubated positive-pressure breaths and 198 of 200 breaths under spontaneous mask ventilation demonstrated a yellow color change (color level 5 or 6), signifying an ETCO2 greater than or equal to 15 mm Hg (2.0 kPa). Repeated-measures analysis of variance revealed no significant differences in infrared ETCO2 values between the two yellow color levels throughout the study period. The associations among color level, infrared ETCO2 determinations, ETT size, and ETT "leak" pressures estimated by Spearman rank correlation analysis were significant only for higher infrared ETCO2 values with higher ETT leak pressures (P less than 0.05). No complications were observed. The Fenem disposable colorimetric ETCO2 detector effectively confirms clinical signs of endotracheal intubation in children when capnography is unavailable.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbon Dioxide↗
PubMed1991

Structural determinants of miscibility in surface films of galactosylceramide and phosphatidylcholine: effect of unsaturation in the galactosylceramide acyl chain.

The Langmuir film balance technique has been used to define the surface structure and determine the mixing behavior of galactosylceramide (GalCer) and phosphatidylcholines in surface phases. To determine the effect of unsaturation on surface behavior, chain-pure GalCer species containing either oleoyl (18:1 delta 9), eicosenoyl (20:1 delta 11), or eicosadienoyl (20:2 delta 11,14) fatty acyl chains were synthesized. Using bovine brain GalCer as a reference, surface pressure versus molecular area (phi-A) isotherms of the pure lipids were measured and analyzed by determining their compressibilities and by using an equation of state for lipid monolayers. This information, when coupled with surface potential versus molecular area (delta V-A) analyses, provides insights into GalCer surface structure in terms of molecular packing and orientation. Lipid mixing behavior was determined by classical approaches which involve analyzing the average molecular area, the average surface dipole moment, and surface pressure as a function of film composition. The results indicate that, in contrast to the complex mixing behavior displayed by bovine brain GalCer and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), chain-pure GalCer species containing either oleoyl, eicosenoyl, or eicosadienoyl fatty acyl chains are miscible with POPC over the entire composition range. Moreover, increasing amounts of GalCer containing eicosenoyl acyl chains systematically elevate dipalmitoylphosphatidylcholine's (DPPC) liquid-expanded-to-liquid-condensed transition pressure. Such behavior is consistent with GalCer being miscible with the liquid-expanded phase of DPPC. Thus, fatty acyl unsaturation is a critical parameter governing the mixing behavior of GalCer with phosphatidylcholine.

Animals↗
PubMed1991

Porcine alveolar and pulmonary intravascular macrophages: comparison of immune functions.

Although a substantial amount of information is available on pulmonary alveolar macrophages (PAMs), little is known about pulmonary intravascular macrophages (PIMs), a separate population of lung macrophages found apposed to the endothelium of pulmonary capillaries. We compared these two populations of lung immunocytes to determine their relative immunological activity. Our results suggest that PAMs are more phagocytic than PIMs; however, PIMs may be more efficient at lysing ingested bacteria than PAMs. Although similar in antibody-dependent cellular cytotoxicity, PIMs are more spontaneously cytolytic than PAMs. Depending upon the effector:target cell ratio studied, the tumoricidal activity of PIMs was less than or equal to that of PAMs. Both cell populations produced the cytokines interleukin-1 and tumor necrosis factor-alpha at similar concentrations. These data suggest that PIMs are immunologically active, although the degree of activity may differ between PIMs and PAMs.

Animals↗
PubMed1991

Atypical mycobacterium soft-tissue infection of the dorsal radial wrist: a possible complication of steroid injection for de Quervain's disease.

Corticosteroid injection into the first dorsal compartment for acute de Quervain's tenosynovitis is an accepted form of therapy. Potential side effects include soft-tissue atrophy, tendon attrition, postinjection neuritis of the superficial radial nerve, systemic reactions, and infection. We present a patient with a Mycobacterium chelonei infection localized to the soft tissue overlying the first dorsal compartment, occurring 3 years after a triamcinolone injection into this area. Histological examination with the polarizing microscope revealed persistent steroid granules in the involved tissue. Successful treatment consisted of complete excision of the involved skin and subcutaneous tissue followed by delayed closure. Systemic antibiotics were not used.

Adult↗
PubMed1991

Fingernail deformities secondary to ganglions of the distal interphalangeal joint (mucous cysts).

Twenty-six nail deformities secondary to ganglions of the distal interphalangeal joint were retrospectively reviewed to assess the important aspects of their management. The patients' ages ranged from 41 to 79 years. The long and index fingers were most commonly involved. A depression or groove was present in 23 of 26 digits reviewed. Two had gross disruption of the nail. Fifty-eight percent of the cysts had spontaneously drained or had been drained by the patient or a physician preoperatively. Degenerative arthritic changes were seen in 87 percent of those with x-rays or a radiology report available. Most underwent surgical removal of the cyst and debridement of associated osteophytes of the distal interphalangeal joint. The cyst was located above the germinal matrix in all but two digits. Osteophytes were found in all 20 digits in which the joint was explored. No recurrences were seen in those available for postoperative follow-up (22 of 25). Normal nail growth was found in 14 of 22, although follow-up was short in one. All eight postoperative nail deformities were quite mild and of little concern to the patient. There was no correlation between preoperative cyst drainage and aesthetic postoperative nail growth. Nail removal at the time of surgery appeared to be unnecessary unless the nail was grossly disrupted.

Adult↗
PubMed1990

Reliability of ratings of anesthesia's contribution to adverse surgical outcomes.

The interrater reliability of physician ratings of anesthesia contribution to adverse outcomes was evaluated. A physician panel reviewed hospital records, anesthesia records, standard data collection forms, and, when available, autopsy reports for 28 patients experiencing severe morbidity or death within 48 hours following anesthesia for surgery. Consensus among reviewers about the contribution of anesthesia to adverse outcomes ranged from 82.1% to 92.9%. Kappa coefficients indicated excellent interrater reliability for the Edwards Scale and rating scale, and good interrater reliability for the percent scale.

Anesthesia↗