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Biomedical subjects

B Barnes

Publications and source records attributed to B Barnes.

At least 19 recordsLinked to original sources
PubMed2001

Epidemiology of invasive Streptococcus pneumoniae infections in the United States, 1995-1998: Opportunities for prevention in the conjugate vaccine era.

CONTEXT: Pneumococcal polysaccharide vaccine is recommended for elderly persons and adults with certain chronic illnesses. Additionally, a recently licensed pneumococcal 7-valent conjugate vaccine has been recommended for use in young children and could dramatically change the epidemiology of pneumococcal disease. OBJECTIVES: To assess pneumococcal disease burden in the United States, estimate the potential impact of new vaccines, and identify gaps in vaccine recommendations. DESIGN AND SETTING: Analysis of data from the Active Bacterial Core Surveillance (ABCs)/Emerging Infections Program Network, an active, population-based system in 9 states. PATIENTS: A total of 15 860 cases of invasive pneumococcal disease occurring between January 1, 1995, and December 31, 1998. MAIN OUTCOME MEASURES: Age- and race-specific pneumoccocal disease incidence rates per 100 000 persons, case-fatality rates, and vaccine preventability. RESULTS: In 1998, overall incidence was 23.2 cases per 100 000, corresponding to an estimated 62 840 cases in the United States. Incidence was highest among children younger than 2 years (166.9) and adults aged 65 years or older (59.7). Incidence among blacks was 2.6 times higher than among whites (95% confidence interval [CI], 2.4-2.8). Overall, 28.6% of case-patients were at least 65 years old and 85.9% of cases in this age group were due to serotypes included in the 23-valent polysaccharide vaccine; 19.3% of case-patients were younger than 2 years and 82.2% of cases in this age group were due to serotypes included in the 7-valent conjugate vaccine. Among patients aged 2 to 64 years, 50.6% had a vaccine indication as defined by the Advisory Committee on Immunization Practices (ACIP). The case-fatality rate among patients aged 18 to 64 years with an ACIP indication was 12.1% compared with 5.4% for those without an indication (relative risk, 2.2; 95% CI, 1.7-2.9). CONCLUSIONS: Young children, elderly persons, and black persons of all ages are disproportionately affected by invasive pneumococcal disease. Current ACIP recommendations do not address a subset of persons aged 18 to 64 years but do include those at highest risk for death from invasive pneumococcal disease.

Adolescent↗
PubMed2001

A phase I-II trial of topotecan and gemcitabine in patients with previously treated, advanced non-small cell lung cancer (LOA-3).

The purposes of this study were to determine the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), toxicity profile, and antitumor activity of topotecan (TOP) and gemcitabine (GEM) combination therapy when administered to patients with previously treated, advanced, non-small cell lung cancer. Both compounds were administered intravenously over 30 min, with TOP on days 1-5 and GEM on days 1 and 5 only. Nineteen patients were treated with 75 courses at three dose levels. The MTD was 0.75 and 400 mg/m2 for TOP and GEM, respectively, with thrombocytopenia and neutropenia as the DLTs. Partial responses were achieved in 3 of 17 patients (18%) with measurable disease. Six patients (32%) had disease stabilization for at least four courses of treatment. The median survival was 10 months from the initiation of TOP and GEM. This combination was relatively well tolerated and exhibited promising antitumor activity in patients with advanced, previously treated, non-small cell lung cancer.

Adult↗
PubMed2001

Threaded cortical bone dowels for lumbar interbody fusion: over 1-year mean follow up in 28 patients.

OBJECT: The authors retrospectively reviewed a series of 35 patients with mechanical low-back or one- to two-level discogenic pain; the patients underwent lumbar interbody fusion in which threaded cortical bone dowels (TCBDs) were placed to treat degenerative disc disease. The purpose of the study was to delineate fusion rates and outcome data in this series of patients. METHODS: The series was composed of 18 women and 17 men whose mean age was 46 years (range 17-76 years). There were nine active cigarette smokers. All patients presented with symptoms consistent with mechanical low-back or discogenic pain, and magnetic resonance imaging revealed degenerative changes related to disc collapse at one or two vertebral levels. For placement of the TCBDs, 23 patients underwent posterior lumbar interbody fusion (PLIF), whereas 12 patients underwent anterior lumbar interbody fusion (ALIF). In all except one patient undergoing PLIF, pedicle screw and rod constructs were used without posterolateral fusion. In all patients undergoing ALIF except one, TCBDs were used as stand-alone devices without supplemental fixation. At follow up the success of fusion was determined by static lumbar radiography and/or computerized tomography scanning. The degree of lumbar lordosis at the diseased level was measured immediately postoperatively and compared with that documented on follow-up radiological studies. Outcomes were assessed using a modified Prolo Scale. Excellent and good outcomes were considered satisfactory, and fair or poor outcomes were considered unsatisfactory. In 28 patients (eight ALIF and 20 PLIF) radiological and clinical follow-up data were considered adequate. The mean follow-up duration was 12.3 months. Overall satisfactory outcome was 60%; 70% satisfactory outcome was noted in PLIF patients and 38% in ALIF patients. Osseous fusion was present in 95% of the patients in the PLIF group and in 13% of those in the ALIF group. Complications included one L-5 nerve root injury and two postoperative wound infections, all in patients who underwent PLIF; in an ALIF patient lateral breakout of one implant occurred at 8 months postoperatively. CONCLUSIONS: Analysis of the mean 12.3 month follow-up data indicates that there is a dramatically higher fusion rate in PLIF compared with ALIF procedures when TCBDs are used. The authors believe that it is important to note that in all the PLIF procedures except one, supplemental pedicle screw/rod constructs were used, whereas in ALIF procedures no supplemental fixation was performed. The results thus suggest that TCBDs are best used in PLIF in conjunction with pedicle screw and rod constructs.

Adolescent↗
PubMed2000

Herniated lumbar disc material as a source of free glutamate available to affect pain signals through the dorsal root ganglion.

STUDY DESIGN: Combined prospective human cohort and prospective controlled animal model. OBJECTIVES: To determine whether free glutamate is available in herniated disc material in concentrations sufficient to diffuse to glutamate receptors and affect the activity of neurons in the dorsal root ganglion that may transmit pain information. SUMMARY OF BACKGROUND DATA: The severity of lumbar radicular pain cannot be fully explained by physical pressure on nerve roots or ganglions. In experimental models, inflammatory processes are relatively modest under conditions of disc herniation. The hypothesis for the current study was that the proteoglycan link and core proteins, which contain high fractions of acidic amino acids, may be a source of glutamate when enzymatically degraded in an environment without glutamate reuptake systems. Glutamate would be free to diffuse to the dorsal root ganglion to affect glutamate receptors. METHODS: Disc material was harvested during surgery from herniated and nonherniated portions in patients undergoing elective lumbar disc surgery and subjected to immunohistochemistry and high-performance liquid chromatography for assessment of the presence of extracellular disc matrix glutamate. Miniosmotic pumps with differing concentrations of radiolabeled glutamate based on human data were implanted in the rat epidural space for 72 hours and dorsal root ganglion (DRG) in the region were harvested. RESULTS: Densitometry of disc matrix demonstrated immunohistochemical evidence for significant extracellular glutamate (P < 0.002). High performance liquid chromatography showed significant concentrations of glutamate in disc material and significantly more in herniated than in nonherniated disc material (P < 0.05). Significant radiolabeling of the dorsal root ganglion after epidural glutamate infusion was found at concentrations two orders of magnitude below measured disc glutamate levels. Autoradiography demonstrated radiolabeling of adjacent DRG. CONCLUSIONS: Glutamate originating from degenerated disc proteoglycan may diffuse to the dorsal root ganglion and effect glutamate receptors. Consideration may be given to treating disc radiculopathy with epidural glutamate receptor antagonists.

Adult↗
PubMed1999

A developmental evaluation process for nurses: enhancing professional excellence.

Healthcare organizations are challenged to provide an environment that enhances professional growth. Miami Valley Hospital responded by examining its evaluation system for clinical nurses and designing a developmental evaluation process. The result is an objective position description outlining global responsibilities of a nurse and a comprehensive, unit-specific assessment of performance. As nurses are guided and nurtured in their development, the opportunities for them to excel are unlimited.

Consultants↗
PubMed1998

Work production and work absorption in muscle strips from vertebrate cardiac and insect flight muscle fibers.

Stretch activation, which underlies the ability of all striated muscles to do oscillatory work, is a prominent feature of both insect flight and vertebrate cardiac muscle. We have examined and compared work-producing and work-absorbing processes in skinned fibers of Drosophila flight muscle, mouse papillary muscle, and human ventricular strips. Using small amplitude sinusoidal length perturbation analysis, we distinguished viscoelastic properties attributable to crossbridge processes from those attributable to other structures of the sarcomere. Work-producing and work-absorbing processes were identified in Ca(2+)-activated fibers by deconvolving complex stiffness data. An 'active' work-producing process ("B"), attributed to crossbridge action, was identified, as were two work-absorbing processes, one attributable to crossbridge action ("C") and the other primarily to viscoelastic properties of parallel passive structures ("A"). At maximal Ca(2+)-activation (pCa 5, 27 degrees C), maximum net power output (processes A, B and C combined) occurs at a frequency of: 1.3 +/- 0.1 Hz for human, 10.9 +/- 2.2 Hz for mouse, and 226 +/- 9 Hz for fly, comparable to the resting heart rate of the human (1 Hz, 37 degrees C) and mouse (10 Hz, 37 degrees C) and to the wing beat frequency of the fruit fly (200 Hz, 22 degrees C). Process B maximal work production per myosin head is 7-11 x 10(-21) J per perturbation cycle, equivalent to approximately 2 kT of energy. Process C maximal work absorption is about the same magnitude. The equivalence suggests the possibility that a thermal ratchet type mechanism operates during small amplitude length perturbations. We speculate that there may be a survival advantage in having a mechanical energy dissipater (i.e., the C process) at work in muscles if they can be injuriously stretched by the system in which they operate.

Animals↗
PubMed1996

A starch-hemoglobin resuscitative compound.

A resuscitative compound in freeze-dried form has been synthesized between a modified starch and a tetremerically stabilized hemoglobin. In order to complex the hemoglobin, the starch has been prepared in mono-, di-, tri-, and tetra-aldehyde moieties. The hemoglobin was stabilized with low molecular weight diacids. Electrophoretic densitometric patterns indicate compound formation. The resulting polymers were characterized with respect to oxygen transport (biotonometry), Hill constant and P50. The in vivo evaluation indicates that these compounds are effective in exchange-transfusion experiments with rats to a level of about 85% replacement of whole blood. The final product is a cost-effective acellular resuscitative compound which can be stored in freeze-dried form at room temperature for extended periods of time. This artificial blood substitute can be reconstituted upon the addition of water.

Animals↗
PubMed1994

Mixtures of erythrocytes and acellular fluids: an in vitro evaluation.

To evaluate the biophysical properties of two acellular resuscitative fluids, experiments were performed using mixtures of these with suspensions of red blood cells. Two acellular resuscitative fluids were synthesized using a diacid to tetramerically stabilized hemoglobin and then complexing it with either a hydroxyethyl starch or a Tetronic Polyol. The new polymers were characterized with respect to the molecular weight, second virial coefficient and intrinsic viscosity. These fluids were then combined with red cells and the following measurements were made: non-Newtonian flow properties, malonamide induced hemolytic kinetics, sedimentation rates and oxygen transport. The in vitro evaluation indicates that these compounds are effective hemodiluents, offer protection to the red cell membrane and do not cause erythrocyte aggregation. The oxygen transport was satisfactory.

Animals↗
PubMed1991

Homotypic antibody responses to fresh clinical isolates of human immunodeficiency virus.

Human immunodeficiency virus type 1 (HIV-1) exhibits extensive genomic and antigenic diversity, which is thought to contribute to the failure of the host's immune response to control infection and prevent clinical progression. Part of this failure may be due to utilization by the virus of antigenic variation as a means to escape protective immune responses. Antibody-escape variants of HIV-1 were studied here using fresh clinical isolates and autologous plasmas. HIV-1 was isolated from the plasma of seven people who were all seropositive for at least 2 years, and symptomatic sometime during that period. Isolated viruses were confirmed as HIV-1 by the presence of reverse transcriptase activity in infected culture supernatants, and by positive immunofluorescence using human monoclonal antibody to HIV-1 core protein. Plasma from these people were positive by Western immunoblot (DuPont) for most major HIV-1 (strain IIIB) antigens. These plasmas neutralized three laboratory strains of HIV-1 (i.e., IIIB, RF, and MN) but did not neutralize the homotypic strain in five cases, and had greatly reduced neutralizing titers against the homotypic strain in two cases. Homotypic neutralizing antibodies were absent in autologous plasma obtained 3 months later. When antibody titers were measured by fixed-cell indirect immunofluorescence assays (IFAs), high titers of IgG (1:6400 to 1:25,600) were detected against HIV-1 IIIB, while low titers of only 1:20 to 1:160 were detected against homotypic viral antigens at the time of virus isolation, and remained low 12 and 16 weeks later. No class IgA, IgD, IgE, or IgM antibodies to homotypic viral antigens, as possible IgG-blocking antibodies, were detected by fixed-cell IFAs. Cross-reactions with heterologous donor's plasmas were observed in some cases, and in these cases the cross-reactions were unidirectional. Live-cell IFAs detected IgG in patient's plasma to HIV-1 IIIB-infected cells but not to cells infected with homotypic isolates. These results suggest that it is common for neutralization-resistant HIV-1 variants to appear during the course of infection, and that all or most antigens of these variants are capable of escaping antibody recognition.

AIDS-Related Complex↗
PubMed1987

Functional outcomes after hip fracture.

The ability to achieve independent ambulation after hip fracture, orthopedic stabilization, and subsequent rehabilitation was studied in 65 inpatients in a specialized geriatric rehabilitation center. The association of 10 factors with the ability to achieve independent ambulation was measured by Kendall's tau B analysis and a two-tailed t test. The 10 factors were sex, age, surgical technique, side of fracture, site of fracture, presence of previous fracture, presence of lower extremity contractures, strength of hip abductor muscles, number of visits to physical therapy, and number of days from surgery to discharge from physical therapy. Measurements were taken at discharge from physical therapy, at 60 days after surgery, and one year after surgery. Fifty-four (83%) of the 65 patients reached independent ambulation at some time between the date of surgery and one year later. At one year after surgery, only 4 of the 65 patients had died. The variables of age, lower extremity contractures, strength of the affected hip abductor muscles, type of surgical technique, number of visits to physical therapy, and number of days from surgery to discharge were associated with independence in ambulation.

Activities of Daily Living↗
PubMed1984

Ambulation outcomes after hip fracture.

Ability to achieve prefracture ambulation status after hip fracture and subsequent rehabilitation was studied in 70 inpatients in a geriatric rehabilitation center. The association of 11 factors with the ability to achieve prefracture ambulation status was measured by chi-square analysis. The 11 factors were age, sex, number of visits to physical therapy, presence of pain in the affected extremity, leg-length difference of 0.5 in or more, side of fracture, motivation, orientation, alertness, previous leg fracture, and surgical repair with a prosthetic replacement or fracture pinning. Forty percent of the entire group returned to their prefracture level of ambulation by the time of discharge from physical therapy. Of the 11 variables studied, only previous leg fracture and the number of visits to physical therapy showed a significant association with the patient's ability to reach prefracture ambulation status.

Age Factors↗
PubMed1984

Labeling of peripheral blood polymorphonuclear leukocytes with indium-111: a new method for the quantitation of in-vivo accumulation of PMNLs in rabbit skin.

A precise method for quantitation of polymorphonuclear leukocyte (PMNL) accumulation in skin in vivo, has been developed so that the proinflammatory effects of various agents can be compared. This method can also be used to evaluate the effect of therapeutic agents on PMNL accumulation in vivo. Rabbit PMNLs were purified from heparinized blood by dextran sedimentation, hypotonic lysis, and separation on Ficoll-Hypaque. The PMNLs were labeled with 3-5 microCi per 10(6) cells of 111In oxine and reinfused coincidentally with different concentrations of different chemotactic and proinflammatory materials injected intradermally into the back. In some experiments, varying concentrations of acetic acid were applied topically. Four to 18 hours later, the rabbits were sacrificed. Eight-millimeter punch biopsies were obtained from the injection sites and counted in a gamma counter. The number of PMNLs infiltrating the dermis was also quantitated in histologic sections. A significant correlation was found between the percent increase in radioactivity and the percent increase in PMNL accumulation morphologically. Dose-response curves were generated using such proinflammatory materials as formyl-methionyl-leucyl-phenylalanine, lipopolysaccharide, activated serum, trypsin, glycogen, and acetic acid. These curves were highly reproducible from animal to animal. Using this assay, we found that as little as 1 microgram of trypsin induced detectable PMNL accumulation. This is 2-3 logs more sensitive than injecting mice intraperitoneally with trypsin. Diisopropyl fluorophosphate-inactivation of trypsin inhibited PMNL accumulation. This sensitive and quantitative bioassay of PMNL accumulation permits evaluation of multiple agents in the same animal, which decreases animal to animal variation.

Acetates↗
PubMed1983

Implementation of an on-line archive for retrieval of laboratory results for outpatients.

An on-line archive of laboratory results designed specifically for ambulatory care areas is described. It is a direct result of paper-flow problems in clinics, which were manifested by numerous phone calls to the laboratory for test results performed up to 10 months ago, and requiring as much as 30 minutes each for retrieval. The archive is incorporated into the result inquiry program of our laboratory computer and is transparent to the user. Utilization of this system by our personnel saves up to 12 hours of work each day. By capturing in a separate file the patient location of each call for outpatient results we are able to identify the clinics that use the telephone for retrieval of test results.

Ambulatory Care↗
PubMed1982

High frequency CT findings within 24 hours after cerebral infarction.

Twenty-six patients with clinically documented acute cerebral infarction were evaluated by computed tomography within the first 24 hr. In 21 patients, subtle mass effects and/or focal areas of decreased attenuation corresponding to areas of clinical deficit were demonstrated. Enhancement occurred in only five of 15 infarctions rescanned after contrast administration. In three of these, the region of infarction became isodense after contrast administration. In a patient with multifocal infarcts, enhancement was the only clue to infarction in one focus. The improved spatial and contrast resolution of current generation scanners appears to have significantly increased the sensitivity of computed tomography in demonstrating acute cerebral infarction and has important clinical application.

Acute Disease↗