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Biomedical subjects

A L Davis

Publications and source records attributed to A L Davis.

At least 37 records · Page 2Linked to original sources
PubMed1993

Accessory cardiac bronchus: CT features and clinical significance.

PURPOSE: The accessory cardiac bronchus is a rare congenital anomaly of the tracheobronchial tree that arises from the medial wall of the bronchus intermedius. This report documents the computed tomographic (CT) appearance of this anomaly. MATERIALS AND METHODS: Six patients with this anomaly were identified. All six underwent CT; three underwent correlative bronchoscopy, and one had both bronchoscopic and surgical confirmation. RESULTS: In all six cases, a distinct airway could be identified originating from the medial wall of the bronchus intermedius. Associated lung parenchymal tissue was identified in four cases, while in three cases a discrete soft-tissue mass was seen, presumably representing vascularized bronchial or vestigial parenchymal tissue. In two cases, the lumen of the airway was filled with debris. CONCLUSION: Recognition of this anomaly is important, as associated clinical complications, including recurrent episodes of both infection and hemoptysis, may be anticipated in a small percentage of patients.

Adult↗
PubMed1991

Role of early fluid resuscitation in pediatric septic shock.

OBJECTIVE: To examine the association of the volume of fluid administered at 1 and 6 hours after presentation, with survival and the occurrence of the adult respiratory distress syndrome, cardiogenic pulmonary edema, and persistent hypovolemia during the resuscitation of children with septic shock. SETTING AND PATIENTS: All pediatric patients with septic shock presenting to the emergency department over a 6-year period and having a pulmonary artery catheter inserted by 6 hours after presentation were identified. METHODS: Patients were analyzed together and in three groups based on fluid volume in the first hour: group 1, less than 20 mL/kg; group 2, 20 to 40 mL/kg; and group 3, more than 40 mL/kg. Adult respiratory distress syndrome was diagnosed by the presence of alveolar infiltrates, hypoxemia, and a pulmonary capillary wedge pressure of 15 mm Hg or less. Cardiogenic pulmonary edema was diagnosed similarly, except the pulmonary capillary wedge pressure was greater than 15 mm Hg. Hypovolemia was diagnosed by the presence of oliguria, hypotension, and a pulmonary capillary wedge pressure of 8 mm Hg or less 6 hours after presentation. RESULTS: We identified 34 patients (median age, 13.5 months). At 1 and 6 hours, respectively, group 1 (n = 14) received 11 +/- 6 and 71 +/- 29 mL/kg (mean +/- SD) of fluid; group 2 received 32 +/- 5 and 108 +/- 54 mL/kg of fluid; and group 3 received 69 +/- 19 and 117 +/- 29 mL/kg of fluid. Survival in group 3 (eight of nine patients) was significantly better than in group 1 (six of 14 patients) or group 2 (four of 11 patients). Adult respiratory distress syndrome developed in 11 patients (32%) and cardiogenic pulmonary edema developed in five patients (15%). Having adult respiratory distress syndrome was associated with increased mortality, but adult respiratory distress syndrome was not increased in any group. Similarly, cardiogenic pulmonary edema was not associated with the fluid volume received or with decreased survival. Hypovolemia occurred in six patients in group 1 and two patients in group 2; all eight subsequently died. CONCLUSION: Rapid fluid resuscitation in excess of 40 mL/kg in the first hour following emergency department presentation was associated with improved survival, decreased occurrence of persistent hypovolemia, and no increase in the risk of cardiogenic pulmonary edema or adult respiratory distress syndrome in this group of pediatric patients with septic shock.

Adolescent↗
PubMed1991

Polypeptide-metal cluster connectivities in Cd(II) GAL4.

Two-dimensional 1H-113Cd correlation NMR spectra have been used to determine the polypeptide/metal cluster connectivities in Cd(II) GAL4. The results show that the protein contains a two metal ion cluster where Cys-11 and Cys-28 are the bridging ligands.

Cadmium↗
PubMed1991

Lichen planus pemphigoides: its relationship to bullous pemphigoid.

Clinical and immunopathological studies of three patients with lichen planus pemphigoides (LPP) were carried out to investigate the relationship between LPP and bullous pemphigoid (BP) and to determine whether the antigen in LPP is the classical BP antigen. LPP is usually considered to be the coexistence of lichen planus with BP. The bullae in LPP were subepidermal and indistinguishable from BP. Indirect immunofluorescence demonstrated antibody binding to the epidermal surface of 1 M NaCl-split skin and mucosae, as in BP. The tissue distribution of the LPP antigen mirrored the distribution of BP in stratified squamous epithelia but was absent from transitional epithelia (pig bladder). Immunoelectron microscopy, both direct (two cases) and indirect (one case), showed binding to the lamina lucida as with BP antigen. Western blotting of epidermal extracts using the patients' sera showed that instead of reacting with the classical bullous pemphigoid antigen (220 kDa in our series), the antisera reacted with a unique band of 200 kDa in addition to the band of 180 kDa found as a minor antigen in bullous pemphigoid, but more commonly in pemphigoid gestationis. The relationship between these antigens awaits molecular characterization. These findings suggest that the target antigen in LPP may be unique.

Adult↗
PubMed1991

Linear IgA dermatosis with severe arthralgia.

Linear IgA dermatosis with severe arthralgia is a rare clinical syndrome. Streptococcal infection may be important in its pathogenesis. The rash and arthralgia respond to dapsone although additional treatment with non-steroidal anti-inflammatory drugs and/or corticosteroids may be necessary. A case is presented which illustrates these features.

Adult↗
PubMed1991

Busulphan/cyclophosphamide conditioning for bone marrow transplantation may lead to failure of hair regrowth.

Following the introduction of bulsulphan and cyclophosphamide (BUCY) conditioning in our unit in 1987, a number of patients noted incomplete scalp hair regrowth following bone marrow transplantation (BMT). Between August 1987 and May 1989, 22 patients had undergone allogeneic or autologous BMT in our unit and we recalled for detailed assessment the 14 who were alive and well at least 6 months post grafting. Six patients had experienced incomplete hair regrowth of varying severity 7-27 months following BMT. All those affected had received BUCY conditioning and the four most severely affected were allogeneic BMT recipients. No patient had received any post-BMT chemotherapy or radiation. None of the patients had evidence of graft-versus-host disease. No laboratory test abnormalities distinguished the affected from the unaffected patients. Despite the relatively small number of patients, our results suggest that BUCY has caused permanent damage to the hair follicles of the affected patients. Prolonged alopecia may markedly impair the quality of life for long-term survivors of BMT and this unexpected complication also has significant medicolegal implications.

Adolescent↗
PubMed1990

Femoral artery cannulation for monitoring in critically ill children: prospective study.

Seventy-seven attempted percutaneous femoral artery cannulations were prospectively evaluated in 74 children. Artery cannulation was successfully accomplished in 73 (95%) cases and lasted for a mean of 6 days. Sixty percent of the catheters were inserted on the first attempt. Fifty-two (71%) patients weighed less than 10 kg and 55 (75%) patients were less than 12 months old. Fifty-one (70%) patients received inotropic support at the time of cannulation, and 27 (37%) eventually died from causes unrelated to catheter insertion. There was one episode each of line-associated infection and transient distal ischemia not resulting in tissue loss, and two episodes of catheter malfunction. In eight (11%) patients, signs of distal vascular insufficiency developed shortly catheter placement and resolved after catheter removal. The development of this complication correlated significantly (p less than .05) with younger age (5.5 vs. 22.3 months). We conclude that femoral artery cannulation has a high degree of success in very small, critically ill children. It should be considered an acceptable alternative to small-vessel cannulation when the latter is not technically achievable, or in the unstable patient where rapid establishment of reliable arterial access is necessary.

Catheterization, Peripheral↗
PubMed1989

Sequential half-body irradiation in lymphomatoid granulomatosis. Report of a case and an immunohistologic study.

A case is presented of a man with ulcerating skin nodules who was diagnosed by histologic and immunohistologic analysis of skin biopsy specimens as having lymphomatoid granulomatosis (LYG). Phenotypic studies showed the majority of the infiltrating cells to be activated CD4+ T-lymphocytes. The disease followed a rapidly progressive course and did not respond to treatment with cytotoxic chemotherapy. The patient developed life-threatening systemic symptoms and involvement of both upper and lower respiratory tracts. After treatment with sequential half-body irradiation he has been in complete remission for 3.5 years.

Adult↗
PubMed1989

Comparisons of French and U.S.A. pediatric intensive care units.

Consecutive admissions to two pediatric intensive care units (PICUs) in France (n = 93) and the United States (n = 248) were compared using admission demographics, and daily therapeutic and severity of illness data. Analysis of the major demographic characteristics revealed that patients in the French PICU were younger (median age; 3 months vs. 31 months, P less than 0.001), and more commonly admitted for emergency reasons (92% vs. 66%, P less than 0.05). General resource utilization was similar in both units. However, important differences in the incidences of use of individual monitoring and therapeutic modalities were present. The United States PICU had higher incidences of invasive monitoring modalities (arterial catheters, 66% vs. 4%, P less than 0.001; central venous catheters, 38% vs. 11%, P less than 0.001; pulmonary artery catheters, 8% vs. 1%, P less than 0.01), while the French PICU had higher incidences of labor-intensive monitoring modalities (strict input/output, 75% vs. 47%, P less than 0.0001; greater than 3 stat blood studies/shift, 69% vs. 45%, P less than 0.0001). Patients in France were more likely to receive mechanical ventilation (81% vs. 56%, P less than 0.0001) and nutritional support (40% vs. 7%, P less than 0.05). Mortality rates in both PICUs were similar and accurately predicted by admission-day severity of illness scores. We conclude that differential resource utilization, possibly arising from different care philosophies, may result in equivalent care.

Critical Care↗
PubMed1989

Atrial natriuretic factor.

ANF is an exciting, newly discovered hormone that has significant potential for furthering our understanding of the complex interactions involved in fluid and electrolyte balance. In addition to effects on water and salt balance, it is a potent vasodilator, as well as inhibitor of renin, angiotensin II, aldosterone, and vasopressin. ANF is primarily produced in the atria, but production in the brain is suggestive of action as a neuropeptide and as a potential regulator of CSF production. Receptors are found throughout the heart, vascular tree, kidney, adrenal gland, and brain. The stimulus for release appears to be atrial stretch, which may be secondary to intravascular fluid changes. It causes hemoconcentration and may be an important regulator of interstitial fluid distribution as well as capillary permeability. Patients with CHF and renal failure have been found to have elevated levels that decrease in response to treatment. Potentially, it may be useful as a therapeutic agent in acute renal failure, CHF and other fluid disturbances. ANF is a testament to the incredible advances in peptide biology. Within 2 years of the discovery, ANF was sequenced and cloned. Since that time, literally thousands of papers describing its actions have been published. Our knowledge about this hormone grows at an exponential rate. It is clear that this hormone is intimately involved in the regulation of fluid and electrolyte balance, vascular tone, and the pathophysiology of CHF but many questions remain unanswered. Continued research will provide many of the missing pieces to this very complex, new hormone system.

Atrial Natriuretic Factor↗
PubMed1988

Injuries in sailboard enthusiasts.

This study was carried out to determine the rate and types of injuries experienced by boardsailors. Results derive from: (a) a review of hospital medical records for water sports injuries, and (b) a questionnaire-interview of 73 athletes windsurfing on waters in the Galveston area during a hurricane and in moderate and light wind conditions. Windsurfers reported 0.22 injuries per 1,000 participant hours. Seventy-six per cent of athletes reported injuries while boardsailing, but only 15 per cent reported significant injuries. The most common reported injuries included lacerations, jellyfish stings, abrasions, muscle strain, sunburn, contusions, and blisters. A small number of athletes reported ligament sprain, ear infection, knee injury, eye injury, and splinters. The large majority of injuries reported are preventable by wearing protective gear, applying sunscreen, avoiding overpowering winds, and selecting safe sailing areas. Four per cent of water-sport injuries requiring hospitalisation resulted when epileptic water-sports participants had a seizure in or near the water.

Adolescent↗
PubMed1988

HLA-DR-positive leucocyte subpopulations in human skin include dendritic cells, macrophages, and CD7-negative T cells.

The immunophenotypes of the HLA-DR-positive leucocyte populations in normal human skin were studied using an extensive panel of monoclonal antibodies, which included antibodies from the Third International Leucocyte Differentiation Antigen Workshop (3rd LDAW). Langerhans' cells (LC) in the epidermis stained with antibodies from CD15c, Groups 10, 12a, 12b and 15, of the myeloid panel and from CD39 of the B-cell panel. However, LC did not react with CD14 antibodies or 63D3, which are frequently used to stain tissue macrophages. In addition to epidermal LC (26 cells/linear mm) a significant population of CD1a-positive cells was identified in the papillary dermis (7 cells/linear mm of overlying epidermis). The dermal HLA-DR-positive leucocytes consisted of three cell populations. The most numerous cell type stained with antibodies to monocytes/macrophages. There were fewer, though substantial, numbers of T lymphocytes (mainly CD7-negative) and the least numerous was the population of CD1a-positive cells. The CD1a-positive cells and the population of dermal cells that stain with monocyte/macrophage markers are both potential antigen-presenting cells for the skin-associated immune system.

Adult↗
PubMed1987

Pneumococcal infection and immunologic response to pneumococcal vaccine in chronic obstructive pulmonary disease. A pilot study.

We assessed the importance of Streptococcus pneumoniae and immunologic response to 14-valent pneumococcal vaccine in a randomized (saline placebo or vaccine) double-blind pilot study involving 103 patients with chronic obstructive pulmonary disease (COPD). Antibody titers, the flora of the sputum, respiratory infections or pneumonias, and deaths were monitored. The patients' antibody titers before immunization were higher than healthy control subjects. Titers rose normally in those vaccinated but declined more rapidly. Differences between the group receiving placebo and vaccine were not significant at 12 and 24 months. The incidence of pneumonia was high before and after vaccine (47/1,000 vs 41/1,000 patient-years). Nonpneumococcal causes predominated (73 percent of pneumonias; 83.4 percent of lethal pneumonias). Isolates from sputum were predominantly nonvaccine types (50 to 62.5 percent). Twenty-seven patients died; pneumonia occurred in six (one pneumococcal in a vaccinated patient) as a terminal complication of other diseases. Thus, although pneumonia occurred frequently in these patients with COPD and contributed to mortality in 22 percent (six) of the 27 deaths, the predominance of nonpneumococcal causes and the data on antibodies and sputum suggest that pneumococcal vaccine may not be as beneficial for patients with COPD as was hoped. More observations are needed.

Adult↗
PubMed1986

Application of the medical anti-shock trouser (MAST) increases cardiac output and tissue perfusion in simulated, mild hypovolaemia.

We have studied the haemodynamic effects of the application of the medical anti-shock trouser (MAST) in 10 healthy subjects in the semi-upright position in order to simulate mild hypovolaemia. Left ventricular end diastolic dimension (EDD) was measured by M-mode echocardiography and cardiac output (CO) by the Doppler ultrasound technique. Forearm blood flow (FBF) was measured by plethysmography and blood pressure (BP) by the standard cuff technique. Systematic increases in MAST pressure of up to 80 mm Hg were applied. EDD increased to a maximum of 9.3% (p less than or equal to 0.01) which was associated with a maximum increase in CO of 31.7% (p less than or equal to 0.05). FBF increased by a maximum of 54.2% (p less than or equal to 0.001) whilst BP increased by a maximum of 12% (p less than or equal to 0.001). These results demonstrate that the application of the MAST is an effective means of transferring blood to the central circulation by compression of the capacitance vessels resulting in significant increases in cardiac output and tissue perfusion. At high pressures there was evidence of compression of resistance vessels, which may be useful in reducing blood loss. The ease and rapidity with which his suit can be applied suggests that it may be useful in the short term treatment of hypovolaemia.

Adult↗
PubMed1985

A possible explanation for the absence of anti-anginal properties of transdermal nitroglycerin units: an echocardiographic study.

The failure of clinical trials to demonstrate any anti-anginal properties of the transdermal nitroglycerin units has resulted in the re-evaluation of one such product, Transiderm-Nitro. Haemodynamic assessment following the application of 10, 20 and 40 cm2 units has been made in eight healthy volunteers over a 6 h period. Measurements of heart rate, blood pressure, stroke volume and left ventricular dimension (by 'M' mode echocardiography) were made 2 h after the application of the units. End diastolic dimension fell by 5.2% and stress by 12.6% implying a reduction in myocardial oxygen consumption. However this was offset by an increase in double product of 10.7% and in circumferential fibre shortening of 23.4%. These results imply that the doses used produce venodilatation leading to a reduction in myocardial oxygen consumption. However this is counterbalanced by the reflex induced increase in heart rate and inotropic state. It suggests therefore that much larger doses are required to produce significant anti-anginal effects.

Administration, Topical↗
PubMed1984

A haemodynamic and pharmacokinetic study to assess a new transdermal nitroglycerin preparation in normal subjects.

A continual application of a transdermal Nitroglycerin ( Nitrodur ) has been haemodynamically and pharmacokinetically assessed in a group of 10 normal healthy volunteers over a 24 h period. There were significant decreases in left ventricular end systolic dimension and end diastolic dimension over this period, demonstrating a continuous haemodynamic effect. A dose related response was not demonstrated, although low plasma nitroglycerin levels produced significant haemodynamic changes. The persistent decrease in left ventricular wall stress implies a reduction in myocardial oxygen consumption. Thus Nitrodur may play an important role in the long term prophylaxis of angina.

Adult↗