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Biomedical subjects

N Williams

Publications and source records attributed to N Williams.

At least 253 records · Page 14Linked to original sources
PubMed1994

Classes of primitive murine megakaryocytic progenitor cells.

We describe high proliferative potential colony-forming cells-megakaryocyte (HPP-CFU-Mk) from mouse bone marrow preparations using known cytokine combinations. These primitive precursors, which generate at least 80 megakaryocytes per colony, were detected from bone marrow populations enriched for primitive cells, either following treatment with 5-fluorouracil (5-FU) or after enrichment from normal bone marrow using immunological procedures. HPP-CFU-Mk were most reproducibly grown in the presence of interleukin-1 (IL-1) plus IL-3 plus IL-6, and mostly grew as a single large aggregate, rarely forming multiple foci. Cell separation studies showed that the HPP-CFU-Mk have membrane properties that characterized these cells as being intermediate between high proliferative myeloid primitive progenitors (high proliferative colony-forming cells [HPP-CFC]) and committed megakaryocyte progenitors (CFU-Mk). The data show that HPP-CFU-Mk can be designated as primitive cells on the basis of their being spared in vivo after 5-FU treatment, their proliferative potential to produce megakaryocytes, and their cofractionation with a proportion of primitive myeloid progenitor cells.

Animals↗
PubMed1993

Complications of circumcision.

Circumcision remains a common operation, with over 30,000 procedures performed annually in the UK, mostly on children. The British Medical Association has recommended that circumcision should be performed only for medical reasons. Despite this, controversy exists over whether too many circumcisions are being performed. Are patients being exposed to an unnecessary operation? It may be argued that in doubtful cases it is easier to proceed to circumcision on the assumption that the attendant risks are low, but the operation is associated with a definite morbidity and rare deaths have been reported. This review considers the spectrum of complications that may result from circumcision and discusses the possible aetiological mechanisms.

Blood Loss, Surgical↗
PubMed1993

Surgical management of perineal and metastatic cutaneous Crohn's disease.

Skin lesions are the commonest extraintestinal manifestation of Crohn's disease. Lesions that develop at sites remote from the gastrointestinal tract and have granulomas on histological examination are termed metastatic cutaneous Crohn's disease. Management is difficult as medical treatment is often ineffective. This report describes the use of surgical debridement of areas of perineal metastatic cutaneous Crohn's disease in five patients, all of whom had failed to improve after a variety of medical treatments. One patient had a poor result with continuing mild perineal discharge and four had a good outcome with complete resolution of symptoms and satisfactory cosmetic results.

Adult↗
PubMed1993

Cultural phenomena and the research enterprise: toward a culturally anchored methodology.

Highlights the points at which culture intersects major phases of the research enterprise--problem formulation, population definition, concept and measurement development, research design, methodology, and data analysis--and influences and constrains what researchers deem worthy of investigation and how they interpret what they observe. These ethnocentric biases inhibit the development of a knowledge base for understanding diverse cultural communities. At each step of the research process, the need to carefully examine and expose the underlying cultural assumptions and to generate and develop alternative choices is emphasized. Guidelines are provided to encourage researchers to be aware of and deliberately make choices toward the development of a culturally anchored methodology that balances the demands for rigor and sensitivity.

Culture↗
PubMed1993

Occlusion of silastic broviac catheters as a result of twisting between the catheter and hub assembly.

Occlusion is a common cause of catheter malfunction during home parenteral nutrition (HPN). We report 5 cases of central venous catheter occlusion, encountered over a 24 month period, which were associated with twisting of the catheter at the hub assembly. One catheter was replaced before the cause of the occlusion was identified. In 4 cases, twisting was noted prior to catheter removal, and this was corrected in three, allowing HPN to continue without catheter replacement. In 1 case the catheter was repaired. The current design of silastic Broviac catheters allows the catheter to twist around the hub assembly. Over-enthusiastic tightening of the cap of the catheter leads to twisting which causes catheter occlusion. A high index of suspicion should be maintained when dealing with catheter occlusion associated with silastic Broviac catheters. Recognition of the problem allows catheter salvage without recourse to catheter replacement.

Journal Article↗
PubMed1993

Polymicrobial catheter sepsis in long term central venous catheters.

We present 2 cases of polymicrobial catheter sepsis in patients with long term central venous catheters who were receiving home parenteral nutrition. Both patients were generally unwell with haemodynamic instability. Attempts at catheter salvage by combined antibiotic and fibrinolytic administration through the central line were unsuccessful and resulted in patient deterioration. Catheters were removed in both patients. We conclude that catheter salvage should be considered very carefully in patients with polymicrobial catheter sepsis and there should be a low threshold for catheter removal in these cases.

Journal Article↗
PubMed1993

How much heparin? A simple in vitro test.

A simple in vitro test to calculate the dose of heparin required to achieve optimal in vivo anticoagulation during surgery has been assessed in 15 patients who subsequently underwent vascular surgery. Heparin was added to four aliquots of patients blood in vitro to give five solutions with heparin concentrations ranging from 0-0.8 units/ml of plasma. The activated partial thromboblastic times (APTT) of each of these samples was then measured and the natural log (ln) of the APTT calculated. The natural log of the APTT in vitro was then plotted against the in vitro heparin concentration. From this linear correlation the concentration of heparin required to achieve an APTT 2.5 times the normal in vitro (Hc) for the 15 different patients was calculated and ranged from 0.4-0.75 units/ml (median 0.47). Based on an estimate of the plasma volume (PV), the bolus dose of heparin given intravenously to each patient to produce an equivalent anticoagulant response in vivo was calculated (Hc x PB). Heparin boli administered ranged from 1000-2000 units (median 1500). The mean in vivo APTT achieved was 77% of the predicted value (range 62%-123%). Such an estimation of an in vivo response, by means of an in vitro test, should help to more accurately predict the effects of heparin in vivo and individualise anticoagulation dosage.

Aged↗
PubMed1993

Protection against ocular and cutaneous infection with herpes simplex virus type 1 by intragastric immunization with live virus.

Intragastric administration of live herpes simplex virus type 1 (HSV-1) was assessed for the induction of humoral immune responses and for protection against ocular and cutaneous challenge with virus. Mice showed no clinical abnormalities following intragastric inoculation with three different strains of virus (Miyama + GC, SC16, and P2C6, a thymidine kinase-defective mutant). Replication of virus was not detected in the oesophagus, superior cervical ganglia or coeliac ganglia of such animals and latent infection was not detected in these ganglia at later times after inoculation. Induction of a mucosal immune response was indicated by the presence of antibody (mainly IgG or IgA)-secreting cells in Peyer's patches. Intragastric immunization gave protection to some extent against ocular challenge and to a greater extent against cutaneous challenge with HSV-1. Following the latter challenge, particularly after intragastric immunization with strains SC16 and Miyama, the establishment of latency was almost completely prevented.

Administration, Oral↗
PubMed1993

Temporal thrombocytopenia after engraftment with defined stem cells with long-term marrow reconstituting activity.

Delayed platelet recovery and altered marrow megakaryocytopoiesis was observed in highly irradiated mice following transplantation with 1000 lineage-negative, stem cell antigen-positive (Lin-Sca-1+) cells. Thirty days after transplantation, the mice were thrombocytopenic. Normal platelet levels were reestablished by 90 days after transplantation. Platelet levels were established from the bone marrow with altered megakaryocytopoiesis, however. Megakaryocyte progenitor numbers were found at reduced levels in the reconstituted marrow at all time points assessed. Bone marrow function was also different in that marrow reserve was also diminished. While the transplantation regime did give long-term reconstitution of blood cells, the quality of the marrow reserve was significantly impaired as revealed by response to further hematopoietic challenge. The data indicate that mice transplanted with a population of highly defined stem cells have perturbed marrow function, one characteristic being an altered process of megakaryocytopoiesis.

Animals↗
PubMed1993

WRULDs: encouraging an ergonomic approach.

The High Court dismissal of an employee's claim for RSI damages has fuelled the debate concerning the diagnosis of work-related upper limb disorders. Dr Nerys Williams identifies musculoskeletal conditions and advocates an ergonomic approach for their prevention and management.

Cumulative Trauma Disorders↗