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Biomedical subjects

W Walker

Publications and source records attributed to W Walker.

At least 19 recordsLinked to original sources
PubMed1992

Monoclonal antibodies to rat liver microsomal cytochrome b5.

Hybridomas obtained by the fusion of spleen cells from rat cytochrome b5-immunized mice with mouse myeloma cells produced five groups of monoclonal antibodies (MAbs) with three mouse immunoglobulin subtypes: IgG1, IgG2b and IgM. All of the MAbs bound strongly to rat cytochrome b5 as measured by radioimmunoassay (RIA). Four clones of MAbs were also strongly immunoreactive with cytochrome b5 when tested by Western blotting, but only one of the MAbs (1-39-2) weakly immunoprecipitated cytochrome b5 in an Ouchterlony double-immunodiffusion test. Two of the MAbs partially inhibited cytochrome b5-mediated NADH cytochrome c reduction catalyzed by liver microsomes (24-36%). Expression of immunodetectable cytochrome b5 was highest in the liver, next highest in the kidney, and quite low in the other tissues examined with MAb 1-17-1 by Western blotting. This MAb recognized homologous cytochrome b5 of human liver microsomes and in homogenates of TK- cells infected with recombinant vaccinia virus encoding human cytochrome b5. These MAbs to cytochrome b5 will be useful for the identification, quantification, and purification of cytochrome b5 from animal and human tissues, and for understanding its role in cytochrome P450 catalyzed drug metabolism and carcinogen activation with respect to tissue, organ and individual differences.

Age Factors↗
PubMed1992

Paranuclear blue inclusions in metastatic undifferentiated small cell carcinoma in the bone marrow.

Paranuclear blue inclusions (PBIs) are frequently identified within metastatic undifferentiated small cell carcinoma (SCC) cells on air-dried bone marrow aspirates stained with Wright's stain. To determine the sensitivity and specificity of this finding, 116 bone marrow aspirates containing metastatic neoplasms were evaluated for the presence and frequency of PBIs. Bone marrow specimens included 47 cases of metastatic SCC of the lung, 13 cases of large cell lymphoma, 19 cases of neuroblastoma, five cases of small, noncleaved cell lymphoma, seven cases of rhabdomyosarcoma, three cases of Ewing's sarcoma, three cases of other sarcomas, and 19 cases of non-small cell carcinoma (adenocarcinoma). PBIs were identified in 40 of 47 (85%) cases of SCC and their frequency varied from 0 to 24% of tumor cells among different cases. In approximately half the cases of SCC, PBIs were identified in 1 to 4% tumor cells; and in eight cases, PBIs were present in 5% or more of tumor cells. PBIs were also identified in two of seven (29%) cases of rhabdomyosarcoma and one case of malignant peripheral nerve sheath tumor, but they were not seen in Ewing's sarcoma, small non-cleaved cell lymphoma, large cell lymphoma, neuroblastoma, or non-small cell carcinoma. In addition, PBIs were not seen in alcohol-fixed, Papanicolaou-stained cytology specimens containing SCC. Ultrastructurally, PBIs may represent phagocytized nuclear/cellular material. PBIs are a feature of small cell carcinoma on air-dried, cytologic material stained with Romanowsky type stains. Their presence may provide diagnostic information with regard to the differential diagnosis of metastatic SCC in the bone marrow. Future studies evaluating non-bone marrow Wright's stained fine-needle aspiration specimens are needed to determine if PBIs are useful in distinguishing SCC from other poorly differentiated tumors in the cytology laboratory.

Bone Marrow↗
PubMed1991

Influence of dietary citric acid and calcium on the bioavailability of orally administered chlortetracycline in piglets.

In a study involving 18 piglets divided into three groups (A, B and C), the effects of dietary calcium and citric acid, and feeding technique on chlortetracycline bioavailability were examined. Groups of 6 animals received a basal diet with either 0.7% (group A) or 1.4% calcium (groups B and C). Citric acid was not included in diets of the first experimental period. In the second period, either 1.5% (groups A and B) or 3.0% (group C) citric acid was added to the diet. In both experimental periods, chlortetracycline was administered once intravenously (7.5 mg/kg b.w.) and once orally (30 mg/kg b.w.). After each administration, blood samples were taken at regular intervals in order to determine chlortetracycline serum concentrations by a microbiological method. Following oral chlortetracycline intake, low dietary calcium or citric acid addition to the diet produced increased chlortetracycline serum concentrations. Chlortetracycline bioavailability was 12.6% at 0.7% dietary calcium, and 9.5% at 1.4% dietary calcium. Enteral chlortetracycline absorption was improved 65% with 1.5% or 3.0% dietary citric acid supplementation. An 8-hour delay of feed intake following oral chlortetracycline intake did not significantly influence chlortetracycline bioavailability.

Administration, Oral↗
PubMed1990

Critical care for clonidine poisoning in toddlers.

Clonidine may be a source of serious toxicity when ingested by toddlers. We describe 11 cases of clonidine ingestion by toddlers (mean dose 0.15 mg/kg; range 0.01 to 0.57). The source of the clonidine was a grand-parent in six of 11 cases. Symptoms included altered level of consciousness (n = 11), miosis (n = 5), bradycardia (n = 8), hypotension (n = 5), apnea and respiratory depression (n = 6), hypothermia (n = 5) and hypertension (n = 3). Therapeutic interventions included naloxone (n = 8) and atropine (n = 4), dopamine (n = 1), fluid resuscitation (n = 4), and endotracheal intubation (n = 1). There were no deaths. Symptoms of clonidine ingestion were typically mild if the dose ingested was less than 0.01 mg/kg, while bradycardia and hypotension occurred usually with doses of greater than 0.01 mg/kg. Apnea and respiratory depression were common when the dose exceeded 0.02 mg/kg. More effective measures are needed to prevent these potentially serious intoxications.

Atropine↗
PubMed1989

The homeless experience: clinic building in a community health discovery-learning project.

The concept of discovery learning is exemplified in this account of four students and their instructor who began and developed a nurse-run clinic for the homeless in a community health project. The students were registered nurses returning for their bachelor's degrees. They experienced frustration at learning the difference between care based on their assessments of patients' needs and care geared to clients' assessments of desired interventions. The journals that they kept reveal self-discovery as well as new respect for other humans. In addition, a new type of community care emerged, which gives all indications of surviving.

Ambulatory Care Facilities↗
PubMed1989

The RGO Generation II: muscle stimulation powered orthosis as a practical walking system for thoracic paraplegics.

The RGO Generation II reciprocating gait orthosis was jointly developed by Louisiana State University Medical Center and Durr-Fillauer Medical, Inc, to overcome four problems encountered with the existing model: 1) The high energy cost of locomotion; 2) the great arm strength required for patients to stand up from the seated position without assistance; 3) difficulty (especially for patients with hamstring contracture) in remaining standing owing to failure of the knee latch to lock except in full extension; and 4) problems in balancing when ambulating on an incline. The RGO Generation II employs concurrent electrostimulation of the rectus femoris and hamstrings to assist in rising and balancing and a ratchet-type latching device to improve safety and stability in standing. Alternating stimulation of the rectus femoris and contralateral hamstrings are used for locomotion. Testing in six patients with thoracic paraplegia demonstrated an average 30+% reduction in energy expenditure at a walking speed of .05 m/s and a 15+% reduction at .37 m/s; improved mobility and better balance on inclines; and unassisted rising in all patients. Walking range was increased from an average of 100 m to an average of 800 m. More research is needed to provide stair-climbing ability and to further reduce energy expenditure.

Adult↗
PubMed1986

Splenunculectomy in thrombocytopenic purpura.

In six patients with thrombocytopenic purpura not cured by splenectomy platelets fell to less than 150 X 10(9)/l within six weeks of splenectomy. They 'failed to respond'. Two underwent splenunculectomy without improvement. Splenuculectomy offered little chance of improvement to published cases who failed to respond but may well be helpful after true relapse.

Child↗
PubMed1985

Natural killer cell activity in childhood acute lymphoblastic leukaemia in remission.

Fifteen children with acute lymphoblastic leukaemia (ALL) in remission receiving maintenance chemotherapy and 12 ALL patients off treatment and in remission were tested for natural killer (NK) cell activity in vitro. Compared with a control population the children with ALL receiving maintenance chemotherapy had low levels of NK cell activity. This effect was not due to a specific reduction in NK cell numbers since proportions of mononuclear cells detected by the monoclonal antibodies HNK-1 (Leu-7) and Leu-11a were normal. Furthermore NK cell activity in patients could only be partially increased by pre-incubation of effector cells with interferon (alpha IFN). These studies confirm the lack of NK cell activity in children with ALL and show that this phenomenon is directly related to functional NK cell impairment. Our study has further shown that this effect is transient since ALL patients off treatment and in remission showed normal levels and augmentation of NK cell activity.

Acute Disease↗
PubMed1985

Platelet values during normal pregnancy.

Blood samples were obtained from 26 healthy women at regular intervals throughout pregnancy and analysed using a Coulter Counter Model S Plus III. The mean values for the various haematological indices at each stage of gestation were first calculated; the platelet count showed a small decrease throughout pregnancy as did haemoglobin concentration while there was an apparent increase in mean platelet volume, platelet distribution width and white cell count. However, analysis of the trends within patients did not always reflect these mean changes; there was considerable variation in platelet count within individuals and the apparent fall in the group as a whole was accounted for by a considerable fall in a few individuals. The assumption that the trends in platelet values determined from groups of patients will indicate how individual pregnant women behave is misleading.

Adult↗
PubMed1983

Role of calcium and calmodulin in activation of the oxyntic cell by histamine and carbamylcholine in the guinea pig.

The role of calcium in stimulation of the oxyntic cell by histamine and carbamylcholine was studied using a sensitive quantitative cytochemical staining technique that measures oxyntic cell hydroxyl ion production (HIP) as an index of acid secretion. Histamine (10(-17)-10(-14) M), carbamylcholine (10(-12)-10(-9) M), and extracellular calcium (10(-7)-10(-3) M) caused a linear, dose-dependent stimulation of the oxyntic cell. EGTA (10(-6) M) inhibited carbamylcholine by 50% but not histamine-stimulated activity. Lanthanum chloride (10(-6) M) caused 100% inhibition of carbamylcholine-induced activity but did not affect histamine-stimulated activity. A maximally effective dose of calcium (10(-4) M) caused additive effects on HIP at low doses of carbamylcholine without alteration of the maximal effect of carbamylcholine. Calcium (10(-4) M) did not enhance the effects of histamine. The calmodulin antagonists, trifluoperazine (10(-5) M), pimozide (10(-5) M), and a naphthalenesulfonamide (W-7), inhibited the integrated response to histamine by 54, 56, and 53%, and that of carbamylcholine by 65, 64, and 99%, respectively. Thus, extracellular calcium per se, stimulates the oxyntic cell. The action of carbamylcholine is completely dependent upon calcium/calmodulin mediation, supporting the concept that cholinergic actions are mediated via calcium-calmodulin events. Although histamine does not require extracellular or membrane calcium events to stimulate the oxyntic cell, calmodulin appears to participate in histamine action.

Animals↗
PubMed1981

Fatal dissemination of cytomegalovirus after bone marrow transplantation.

The clinical course and necropsy findings are described of an 11-year-old child found to have active cytomegalovirus infection at the time of bone marrow transplantation for acute lymphoblastic leukaemia. Attention is drawn to the presence of primitive mononuclear cells of uncertain origin in the regenerating bone marrow.

Bone Marrow↗