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Biomedical subjects

B Clark

Publications and source records attributed to B Clark.

At least 199 records · Page 11Linked to original sources
PubMed1965

The isolation and properties of epithelial-cell "ghosts" from rat small intestine.

1. The preparation of gram quantities of isolated epithelial-cell ;ghosts' from mucosal scrapings of rat small intestine is described. The method involves dispersing the tissue by gentle homogenization in 6% dextran in Krebs-Ringer phosphate, pH7.4, followed by filtration through nylon cloth and sedimentation by low-speed centrifuging. 2. The isolated epithelial-cell ;ghosts' contained all of the DNA, but only 52% of the protein and 53-57% of the RNA of the original homogenate. They contained most of the activity of the following enzymes found in the homogenate: aminopeptidase (71%); alkaline beta-glycerophosphatase (82%); invertase (92%); adenosine triphosphatase (93-116%); acid beta-glycerophosphatase (83%); nonspecific esterase (76%); succinate dehydrogenase (96%). Only small proportions of the total lactate-dehydrogenase (10%) and phosphoglucose-isomerase (2%) activities found in the homogenate were recovered in the isolated cell ;ghosts'. 3. The epithelial-cell ;ghost' preparation did not respire unless cofactors and substrates were added, and did not consume glucose or produce lactic acid from glucose. 4. The effect of varying the composition of the homogenization medium was studied. Concentrations of dextran (mol.wt. 15x10(4)) from 1 to 12%, solutions of dextrans (all at 6%) with mol.wt. varying between 3.6x10(4) and 2x10(6), and a solution of 8% polyethylene glycol (mol.wt. 4000) served equally well for the production of epithelial-cell ;ghosts'. Two of these solutions, however, 12% dextran (mol.wt.15x10(4)) and 6% dextran (mol.wt. 2x10(6)), were too viscous to allow the complete sedimentation of the cell ;ghosts' at low relative centrifugal forces. Omission of either Krebs-Ringer phosphate or dextran from the medium resulted in almost complete cell breakage during the homogenization. 5. The isolated cell ;ghosts' were used as a starting material for subcellular fractionation of rat intestinal mucosa by differential centrifugation. The distributions of protein and succinate-dehydrogenase activity among the fractions were compared with corresponding values in fractions isolated by differential centrifugation of mucosa homogenized in 0.3m-sucrose-5mm-EDTA, pH7.4. The method in which cell ;ghosts' were used as starting material gave a better separation and cleaner fractions than the method in which untreated mucosal scrapings were used.

Acid Phosphatase↗
PubMedDate not supplied

Evaluation of a neuraminidase detection assay for the rapid detection of influenza A and B virus in children.

A prototype version of a new diagnostic assay for influenza A and B (Zstat Flutrade mark) based on detection of viral neuraminidase was evaluated and compared to culture in 196 clinical samples. Children with respiratory illnesses were prospectively evaluated at a pediatrician's office and at a large children's hospital using the neuraminidase assay and viral culture performed on respiratory secretions. Influenza virus was isolated from 51 samples and 83 were positive by the neuraminidase assay. When compared to culture the sensitivity of the assay was 96%, specificity was 77%, positive predictive value was 59%, and negative predictive value was 98%. Testing in the laboratory of pure cultures of bacteria and non-influenza viruses frequently found in the respiratory tract showed 0% cross-reactivity with the neuraminidase assay and 100% specificity for influenza virus in vitro. This new assay provided useful information for the preliminary diagnosis of influenza A and B infections and appears to be suitable for both point-of-care use in the physician's office and rapid diagnosis in a virology laboratory. The high sensitivity makes it particularly useful as a screening test for exclusion of influenza A and B infections. To confirm the diagnosis and exclude a false-positive result, as well as to determine the influenza virus type, a viral culture may be considered.

Animals↗
PubMedDate not supplied

The Suess-Urey mission (return of solar matter to Earth).

The Suess-Urey (S-U) mission has been proposed as a NASA Discovery mission to return samples of matter from the Sun to the Earth for isotopic and chemical analyses in terrestrial laboratories to provide a major improvement in our knowledge of the average chemical and isotopic composition of the solar system. The S-U spacecraft and sample return capsule will be placed in a halo orbit around the L1 Sun-Earth libration point for two years to collect solar wind ions which implant into large passive collectors made of ultra-pure materials. Constant Spacecraft-Sun-Earth geometries enable simple spin stabilized attitude control, simple passive thermal control, and a fixed medium gain antenna. Low data requirements and the safety of a Sun-pointed spinner, result in extremely low mission operations costs.

Astronomy↗
PubMedDate not supplied

Cardiovascular actions of DPI 201-106, a novel cardiotonic agent.

DPI 201-106 (4-[3-(4-diphenylmethyl-1-piperazinyl)-2-hydroxypropoxy]-1H-indole -2- carbonitrile) is characterized by a marked cardiotonic activity. The compound exerted positive inotropic effects in anesthetized and conscious dogs, pithed open-chest cats, and isolated hearts of cardiomyopathic hamsters and vanadate-treated guinea-pig atria. Left ventricular dP/dtmax was increased in anesthetized dogs after i.v. injection of 0.2 and 2 mg/kg DPI 201-106 (34 +/- 6 and 104 +/- 18%, respectively) and in unanesthetized dogs after oral doses of 2-8 mg/kg (22 +/- 3 to 50 +/- 5%, respectively). In most experiments, the compound lowered blood pressure and heart rate. Stroke work and left ventricular work were almost unaffected by DPI 201-106, and oxygen consumption and cardiac efficiency remained unchanged in open-chest dogs. Studies of the mechanism of action of DPI 201-106 lead to the conclusion that its positive inotropic effect is not explainable either by beta-stimulation or by liberation of catecholamines. This was shown in anesthetized dogs and pithed open-chest cats pretreated with propranolol and reserpine.

Animals↗
PubMedDate not supplied

A comparison of outpatient cardiac and pulmonary rehabilitation patients.

PURPOSE: Although cardiac and pulmonary rehabilitation are frequently considered together, differences in the two populations have not been evaluated adequately. METHODS: This study compared patients who were referred to outpatient cardiac and pulmonary rehabilitation over a 1-year period at the authors' institution. Fifty-five cardiac rehabilitation patients (CR) and 47 pulmonary rehabilitation patients (PR) were studied with respect to age, gender, weight, smoking history, functional status, employment status, numbers and types of diagnoses and medications, and number of recent hospitalizations and hospital days. RESULTS: Cardiac rehabilitation patients were approximately 7 years younger, smoked less, were somewhat heavier, had a markedly better functional status, and were more likely employed than their counterparts in pulmonary rehabilitation. In addition, this group had fewer diagnoses and used fewer medications than PR patients. The number of hospitalizations and hospital days in the year preceding rehabilitation, however, were greater in CR patients than in PR patients. CONCLUSIONS: CR patients and PR patients are quite distinct with respect to demographics, functional status, comorbidity, and hospital resource consumption.

Age Distribution↗
PubMedDate not supplied

Three-dimensional reformation of skeletal abnormalities using computed tomography.

A new technique for evaluation of skeletal pathology is described. The use of three-dimensional reformations based on conventional computed tomographic imaging is a technique that has been used by craniofacial surgeons since 1982 and more recently by orthopedic surgeons at the Adelaide (Australia) Children's Hospital for evaluation of pediatric skeletal pathology. Four cases are presented that demonstrate our early experience with the technique. Three-dimensional reformation is an effective method of translating conventional computed tomographic scans into a readily understood three-dimensional image. We believe that the method will be of increasing value in the evaluation of pediatric skeletal pathology.

Adolescent↗
PubMedDate not supplied

Clinical, genetic and histopathologic findings in two siblings with muscle-eye-brain disease.

PURPOSE: We present the clinical, genetic and histopathologic findings in two siblings with Muscle-Eye-Brain Disease (MEB-D), an autosomal recessive disease characterized by mental retardation, muscular dystrophy, retinal hypoplasia and brain abnormalities. METHODS: Clinical, histopathologic and gene mapping studies of a family with two normal and two children with MEB-D. RESULTS: Two siblings presented in the first few months of life with developmental delay, hypotonia, and strabismus. MRI of the brain showed colpocephaly, pontine and cerebellar atrophy, and diffuse white matter disease. Both patients were blind and had high myopia, strabismus, and retinal and optic nerve abnormalities. The older boy had glaucoma. Both children died from uncontrolled seizures. There was retinal, choroidal and RPE atrophy and optic nerve hypoplasia on ocular histopathology. Both patients shared the same parental haplotypes at the MEB locus on chromosome 1p, while an unaffected sibling did not, indicating possible linkage to the MEB locus. CONCLUSIONS: Patients with MEB-D have severe visual impairment from retinal and optic nerve hypoplasia. High myopia appears to be a consistent finding. The ocular manifestations of MEB-D appear to be distinct from those of patients with Walker-Warburg syndrome.

Abnormalities, Multiple↗
PubMedDate not supplied

Collaborative preceptor training: a creative approach in tough times.

Rapid changes in the health care environment have challenged educators to find more efficient methods of developing nurses. These demands are leading to the use of collaborative approaches to education. Nurse educators have also found that they have to rely on preceptors for orientation of new employees. The Texas Medical Center Collaborative Preceptor Program was developed in 1989 to prepare nursing preceptors for all nine participating institutions. The goals of the program were to increase efficient use of instructor time, standardize preceptor preparation in the Texas Medical Center, and offer more programs and prepare more nurses per year than each individual institution could do alone. There were many unexpected benefits as well, and future plans for collaboration are already being formulated.

Education, Nursing, Continuing↗
PubMedDate not supplied

CD20-directed antibody-mediated immunotherapy induces responses and facilitates hematologic recovery in patients with Waldenstrom's macroglobulinemia.

Waldenstrom's macroglobulinemia (WM, lymphoplasmacytic lymphoma) is a B-cell lymphoproliferative disorder in which CD20 is expressed on tumor cells from most patients. Several small studies have suggested a benefit from the anti-CD20 monoclonal antibody rituximab (Rituxan, MabThera) in patients with WM. In this retrospective study, we examined the outcome of 30 previously unreported patients with WM who received treatment with single-agent rituximab (median age 60; range 32-83 years old). The median number of prior treatments for these patients was 1 (range 0-6), and 14 patients (47%) received a nucleoside analogue before rituximab therapy. Patients received a median of 4.0 (1-11.3) infusions of rituximab (375 mg/m2). Three patients received steroids with their infusions for prophylaxis of rituximab-related infusion syndrome. Overall, treatment was well tolerated. Median immunoglobulin M (IgM) levels for all patients declined from 2,403 mg/dL (range 720-7639 mg/dL) to 1,525 mg/dL (range 177-5,063 mg/dL) after rituximab therapy (p = 0.001), with 8 of 30 (27%) and 18 of 30 (60%) patients demonstrating >50% and >25% decline in IgM, respectively. Median bone marrow lymphoplasmacytic (BM LPC) cell involvement declined from 60% (range 5-90%) to 15% (range 0-80%) for 17 patients for whom pre- and post-BM biopsies were performed (p < 0.001). Moreover, 19 of 30 (63%) and 15 of 30 (50%) patients had an increase in their hematocrit (HCT) and platelet (PLT) counts, respectively. Before rituximab therapy, 7 of 30 (23.3%) patients were either transfusion or erythropoietin dependent, whereas only 1/30 (3.3%) patients required transfusions (no erythropoietin) after rituximab. Overall responses after treatment with rituximab were as follows: 8 (27%) and 10 (33%) of the patients achieved a partial (PR) and a minor (MR) response, respectively, and an additional 9 (30%) of patients demonstrated stable disease (SD). No patients attained a complete response. The median time to treatment failure for responding (PR and MR) patients was 8.0 months (mean 8.4: range 3-20+ months), and 5.0 months (mean 6.1; range 3-12+ months) for patients with SD. These studies therefore demonstrate that rituximab is an active agent in WM. Marked increases in HCT and PLT counts were noted for most patients, including patients with WM who had MR or SD. A prospective clinical trial to more completely define the benefit of single-agent rituximab in patients with WM has been initiated by many of our centers.

Adult↗
PubMedDate not supplied

Surgical treatment of metatarsus adductus using a combined soft tissue and osseous approach.

Children between 6 and 8 years of age with metatarsus adductus deformity have been considered to be in the gray zone for surgical correction. Should osseous or soft tissue procedures be implemented to reduce the adducted attitude of the metatarsals? The literature clearly describes one or the other and the intermediary chondrotomy procedure described by Johnson. The use of a combined approach has not been presented. The present authors offer a brief review of metatarsus adductus, and two case reports using a modified, combined approach. Two 7-year-old girls presented with bilateral resistant metatarsus adductus deformities. The authors contend that the first and fifth metatarsals are the major deforming forces in this age group, and may be corrected with base wedge osteotomies, while the central three metatarsals are more amendable to capsular and ligamentous releases. Advantages of soft tissue procedures on the central rays include avoidance of extensive dissection, creating less trauma and avoidance of the need for internal fixation. The obvious disadvantage is the inability to adequately reduce the deformity. This can be assessed intraoperatively. These authors, therefore, conclude that this modified surgical approach is a viable alternative to the previously described procedures for resistant metatarsus adductus.

Bone Wires↗