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Biomedical subjects

D J Wilson

Publications and source records attributed to D J Wilson.

At least 145 records · Page 8Linked to original sources
PubMed1993

Verbal communication of ventilator-dependent patients.

OBJECTIVE: To assess whether communication capabilities of ventilator-dependent patients are improved by the use of the Passy-Muir unidirectional valve. DESIGN: Prospective study. SETTING: An 18-bed multidisciplinary intensive care unit (ICU) at the University Hospital, Las Palmas, Spain. PATIENTS: Ten chronic ventilator-dependent patients who had undergone tracheostomy and met the following criteria: ability to eliminate tracheobronchial secretions in order to maintain a patent and unobstructed airway, adequate gas exchange while ventilated with an FIO2 of < or = 0.4 (Pao2 > 60 torr [8 kPa]), Paco2 of < 55 torr (7.3 kPa), normal hemodynamics without the need for administration of vasopressors, and normal mental state. Eight patients presented with pulmonary disease, and two presented with neuromuscular disease. INTERVENTIONS AND METHODS: Before attaching the Passy-Muir valve, the following procedures were performed: a) suction of tracheal and pharyngeal secretions; b) deflation of the tracheostomy tube cuff; c) increase in the ventilator's tidal volume setting to maintain the inspiratory pressure before cuff's deflation; d) set peak inspiratory pressure alarm and disconnect expiratory volume alarm. The valve was then connected between the tracheostomy tube and the Y-shaped piece of the ventilator's circuit. Respiratory movements, arterial blood gases, peak inspiratory pressure, respiratory rate, quantity of secretions, and changes in sense of smell were monitored during the study. The valve's efficacy was evaluated according to the patient's ability to talk and be understood during the entire respiratory cycle. RESULTS: The Passy-Muir valve was effective in improving communication in eight of ten patients who, during its use, presented insignificant cardiorespiratory changes, decreased secretions, and effected considerable improvement in well-being. Its use was impossible in two patients: one with severe pulmonary disease because cuff deflation prevented adequate ventilation, and one patient with neuromuscular disease and laryngopharyngeal dysfunction. CONCLUSIONS: The Passy-Muir unidirectional valve allows ventilator-dependent patients to talk and communicate without assistance. Patients felt better and were motivated to participate in their own care.

Adult↗
PubMed1993

Systemic and renal hemodynamic differences between FK506 and cyclosporine in liver transplant recipients.

Immunosuppression after transplantation is complicated by hypertension and nephrotoxicity, reflecting widespread vasoconstriction associated with CsA. FK506 is a novel alternative immunosuppressive agent, structurally unrelated to CsA. These studies compared systemic and renal vascular changes developing in the initial 4 weeks after liver transplantation in patients treated with FK506 (plus PRED) and CsA (plus PRED and AZA). We studied arterial pressure, cardiac index (pulsed doppler ultrasound), and systemic resistance index (SVRI) before and weekly after liver transplant in 32 patients treated with CsA (2 mg/kg initial dose plus PRED; median dose at week 4, 30 mg/day) and 14 patients treated with FK506 (0.15 mg/kg/day initial dose and PRED; mean week 4 dose, 12.5). Renal plasma flow and glomerular filtration rate (GFR) were measured by clearance of para-amino hippurate and 125-iothalamate. Renin activity, aldosterone, and urinary prostanoids were measured by RIA. Pretransplant pressures and hemodynamics reflected low SVRI and increased cardiac index typical of end-stage liver disease. After transplantation, SVRI and pressures rose in both groups, but after week 2, SVRI was lower in patients treated with FK506. This was associated with less prevalent clinical hypertension during the subsequent 4 months (4/14 FK506 (28%) vs. 25/32 (78%) CsA, P < 0.01). By contrast, renal blood flow and GFR fell in both treatment groups similarly, whereas renal vascular resistance rose. Urinary 6-keto-PG-F1-alpha was suppressed in all transplant recipients, but to a greater degree in FK506-treated patients. This value correlated directly to post-transplant GFR (r = 0.48, P < 0.001). These data indicate that FK506-based immunosuppression differs from CsA by inducing less systemic vasoconstriction and hypertension. Renal vasoconstrictive effects were at least as great as those seen with CsA, however, and indicate that nephrotoxicity will remain a common feature to both regimens.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Profound platelet degranulation is an important side effect of some types of contrast media used in interventional cardiology.

BACKGROUND: Thrombotic complications occurring during coronary angiography and percutaneous transluminal coronary angioplasty (PTCA) are relatively frequent and can be influenced by the type of radiographic contrast media used. Low osmolar contrast media (LOCM), both ionic and nonionic, have been considered to be safer than the older high osmolar contrast media (HOCM), causing less haemodynamic and symptomatic side effects. Recently, however, nonionic LOCM have been associated with an increased incidence of thrombotic events, including coronary occlusion and stroke. METHODS AND RESULTS: The effects of commonly used contrast media on platelets in native blood were investigated using immunolabeling and flow cytometry to detect platelet activation in vitro. A nonionic LOCM (Omnipaque) caused profound platelet degranulation in nearly 80% of platelets compared with 2 to 3% of platelets in the control. Conversely, an ionic HOCM (Urografin) caused only 25% degranulation, whereas an ionic LOCM (Hexabrix) caused no platelet activation and, furthermore, it inhibited the effects of thrombin on platelets. Platelet degranulation, quantified by immunolabeling, was paralleled by release of beta-thromboglobulin and platelet factor 4 from platelet alpha-granules. Blood from patients anticoagulated with heparin and pretreated with standard-dose aspirin in preparation for PTCA showed the same pattern of contrast media-induced platelet activation as normal subjects. CONCLUSIONS: These results suggest that the type of contrast media used during invasive imaging of the vasculature could have a significant effect on platelets. Platelet degranulation within a PTCA-damaged vessel would be increased by a nonionic contrast medium, releasing procoagulant molecules and platelet-derived growth factors into the damaged vessel lumen, which might contribute to acute thrombosis and the initiation of the restenosis process.

Adult↗
PubMed1993

Can MRI of the knee affect arthroscopic practice? A prospective study of 58 patients.

We made a prospective study of 58 patients with suspected internal derangement of the knee. They were examined by magnetic resonance imaging using 3-D gradient echo intermediate-weighted studies before having an arthroscopy. The preoperative clinical assessment was found to have a diagnostic sensitivity of 77% and a specificity of 43%, compared with 100% and 63% respectively for magnetic resonance imaging. Comparison of magnetic resonance imaging and arthroscopy confirmed the accuracy of magnetic resonance imaging in the diagnosis of internal derangement but the results for articular cartilage lesions were much less good, with a sensitivity of only 18% but a specificity of 100%. Acceptance of the magnetic resonance imaging findings could have resulted in a 29% reduction in the number of arthroscopies without missing any significant meniscal lesion.

Adolescent↗
PubMed1993

The appearance of stippled retinal pigment epithelial detachments. A sign of occult choroidal neovascularization in age-related macular degeneration.

The clinical source of 62 eyes that had been coded for macular degeneration and fibrovascular retinal pigment epithelial (RPE) detachment on fluorescein angiography was reviewed; 17 eyes had signs of a choroidal neovascular membrane (CNVM) at initial examination, and 30 eyes developed a definite CNVM during follow-up examination. Thus, 47 of the 62 eyes (76%) developed a CNVM in association with fibrovascular RPE detachments. Features of fibrovascular RPE detachments include: 1) focal, tiny hyperfluorescent spots at the level of the RPE arising in the mid and late frames of the angiogram, which do not correspond to drusen or foci of depigmentation (stippled hyperfluorescence); 2) intensification of these spots in the later stages of the angiogram; 3) slight enlargement of the spots in the late frames of the angiogram; 4) occasional presence of scant overlying subretinal fluid; and 5) minimal elevation of the RPE. Fibrovascular RPE detachments appear to be a distinct form of an RPE detachment. It is concluded that this sign is associated with a high risk of developing a frank CNVM and is thus a reliable indicator of occult neovascularization.

Aged↗
PubMed1993

Association of Mycobacterium paratuberculosis infection with reduced mastitis, but with decreased milk production and increased cull rate in clinically normal dairy cows.

Approximately 45 Holstein cows that were Mycobacterium paratuberculosis-positive on the basis of fecal culture results were maintained at any one time in a 210-cow dairy herd. Farm management participated in the New York State Paratuberculosis Eradication Program. Paratuberculosis-positive cows were grouped separately from paratuberculosis-negative cows, but they were otherwise managed identically. During a 1-year study, 180 paratuberculosis-negative cows and 113 clinically normal paratuberculosis-positive cows were identified. Quarter milk samples (n = 6,100) were aseptically collected for microbiologic culture of mastitis pathogens from paratuberculosis-negative cows, and 3,129 quarter samples were obtained from paratuberculosis-positive cows. Dairy Herd Improvement Association (DHIA) records were used to monitor milk somatic cell count linear scores, mature equivalent milk production, new mastitis infections, and chronic mastitis infections. For second-lactation cows greater than 100 days in milk production, and increasing with age beyond that point, paratuberculosis-positive cows had lower mature equivalent milk production than did negative herdmates. Rates of new and chronic mastitis infections, as measured by DHIA linear scores were significantly (P < 0.05, P = 0.05, respectively) lower in cows with nonclinical paratuberculosis. Infected cows were culled from the herd at a faster rate than were paratuberculosis-negative herdmates. Therefore, paratuberculosis was associated with financial loss attributable to reduced milk production and increased culling of infected cows.

Animals↗
PubMed1993

Early embryonic angiogenesis in the chick area vasculosa.

The rate and pattern of growth as well as vessel ultrastructure of the area vasculosa were examined in the chick. The embryos were grown in shell-less culture after 3 d in ovo and staged according to Hamburger & Hamilton (1951) and the rate of increase in the diameter of the area vasculosa was measured. This revealed an increase in the area vasculosa diameter of 0.4 +/- 0.02 mm h-1 (n = 62) for embryos between stages 15 and 20. To determine the growth pattern of the sinus terminalis (the advancing edge of the area vasculosa), a marked length of the sinus was photographed at hourly intervals over a period of 9 h. It was found that this vessel grows by new vessels forming external to the sinus in the form of parallel plexuses, one of which then replaces the original sinus as the major route of bloodflow. Ultrastructurally the capillaries of the area vasculosa were simple tubes of endothelial cells, lacking a basement membrane. The endothelial cell cytoplasm contained only a few organelles, mainly mitochondria and rough endoplasmic reticulum. These findings indicate that the chick area vasculosa capillaries bear similar structural and growth characteristics to those associated with tumour angiogenesis and suggest that they may prove to be a useful model system for studying the factors involved in pathological angiogenesis.

Animals↗
PubMed1993

Survival at low dose in asynchronous and partially synchronized Chinese hamster V79-171 cells.

In an earlier study using cell sorting techniques to define the radiation survival response of asynchronous Chinese hamster V79-171 cells more accurately, we found evidence of substructure in the response at low dose. In the present work we have attempted to show that this substructure arises from the subpopulations of sensitive (G1, G2 phase) and resistant (late S phase) cells which are present in asynchronously dividing cultures but which are not resolved by conventional survival assays. Partially synchronized cells were produced by exposure to 1 mM hydroxyurea for 12 h and were harvested 15 min later, yielding a population of viable cells at or just beyond the G1/S-phase boundary. Parallel experiments were carried out with asynchronous cells. The average of repeated measurements of the radiation survival response of asynchronous cells again showed a significant difference (P = 0.002 to 0.009) between the alpha and beta values evaluated from the data for the low-dose range, 0-2.8 Gy, and the high-dose range, 2.8-14 Gy. For G1/S-phase cells, however, there was no significant difference between the values of alpha and beta for the low-dose and high-dose ranges (P > 0.5). The results thus support the hypothesis that the observed substructure in the asynchronous response is due to resolution of subpopulations of different radiosensitivities, and they illustrate the advantage of the cell sorter assay for accurate measurements of cell survival, particularly at low dose.

Animals↗
PubMed1993

The first 50 liver transplants in New Jersey.

New Jersey's first liver transplant was performed on February 14, 1989, at UMDNJ-New Jersey Medical School. By May 1992, 50 patients, ranging in age from 16 to 65 years, had been transplanted. Liver transplantation is an accepted method of treatment for end-stage liver disease.

Female↗
PubMed1992

Milk production, water consumption, and somatic cell count responses of cows subject to one to two volts of alternating current.

A dairy farm located in central New York was visited because of complaints of electrical shock in the farmhouse shower and the milk house sink. As much as 2 volts AC of potential difference was measured between the waterline and the cow platform (cow-contact voltage). Voltage was coming from the primary neutral wire. The farm's electrical service was modified so that the farmstead could be connected or disconnected from the primary neutral wire at 2-week intervals for 12 weeks. When connected to the primary neutral wire, voltage between waterline and floor ranged between 0 and 1.8 volts, producing estimated current flow through cows of 3.6 to 4.9 mA; when disconnected from primary neutral wire, voltage between waterline and floor was less than 0.1 volt. There was no difference in mean milk production, bulk tank milk somatic cell count, or water consumption among periods when cows were exposed or unexposed to voltage. Despite statistical nonsignificance, the values for somatic cell count were lower and water consumption was higher when cows were exposed to voltage than when they were not.

Animals↗
PubMed1992

Living bone grafts.

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Bone Transplantation↗
PubMed1992

Hemifacial microsomia: developmental consequence of perturbation of the auriculofacial cartilage model?

The cause of hemifacial microsomia (HFM) is currently the subject of much investigation. Despite a large body of clinical and experimental data, little is certain other than the heterogeneity of this malformation complex. Here we suggest that some of the cases previously designated as being multifactorial in origin may be interpreted instead as resulting from a single-gene mutation, by applying a stochastic single-gene model. A variety of models of the pathogenesis of HFM have been described, including the proposal that local embryonic haemorrhage is a causal mechanism. More recently, it has been suggested that an interference in chondrogenesis is primarily responsible for the HFM phenotype. In this paper direct experimental evidence, based on surgical interference of mandibular development in the chick embryo, is applied in favour of the latter concept. In particular, asymmetrical perturbation of Meckel's cartilage has been shown to result in asymmetry of the mandible, and it is proposed that, irrespective of cause, the skeletal pathogenesis of HFM primarily involves the auriculofacial cartilage model.

Facial Asymmetry↗
PubMed1992

Intraocular lymphoma. Immunopathologic analysis of vitreous biopsy specimens.

Immunologic analysis of cell surface markers (immunophenotyping) has become a standard procedure in the evaluation of systemic lymphomas. However, attempts to apply these techniques to intraocular lymphoma have not been uniformly successful. We successfully immunophenotyped five consecutive cases of intraocular lymphoma using immunoperoxidase surface marker analysis of cytocentrifuged specimens in two cases and flow cytometry in three. In all five cases, a monoclonal B-cell population was unequivocally present. Contrary to previous reports, we found surface marker analysis of vitreous biopsy specimens to be helpful in the diagnosis and treatment of intraocular lymphoma. Not only did it support the cytologic diagnosis but it allowed comparison of the immunophenotype of vitreous infiltrates with that of previous or subsequent lymphomatous lesions from nonocular sites.

Aged↗
PubMed1992

Arteriographic study of the rabbit lower limb.

The rabbit hind limb has been used extensively as an orthopaedic model in the investigation of fracture pathology and healing and the effects of vascular abnormalities. However, a detailed description of the normal arterial supply appears to be absent from the literature. A study of the entire arterial vasculature has been undertaken using a lead oxide injection technique developed for this and other orthopaedic studies. This technique has proved reliable and inexpensive, giving high-quality arteriography, which is easily interpreted. Accurate description of the arterial anatomy is possible without the need for repeated dissection. The rabbit lower limb shows some interesting variations in blood supply, particularly below the knee. The foot has three distinct patterns of blood supply, depending on the presence or absence of the peroneal artery and the degree of dominance of the dorsalis pedis artery. This arrangement has not previously been described and differs from the situation in other mammals. The arteriographic technique and the anatomical description have allowed the interpretation of changes occurring in the vasculature after injury in a fracture model.

Angiography↗