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Biomedical subjects

D Bennett

Publications and source records attributed to D Bennett.

At least 109 records · Page 6Linked to original sources
PubMed1993

Oligonucleotide fingerprinting of isolates of Candida species other than C. albicans and of atypical Candida species from human immunodeficiency virus-positive and AIDS patients.

Oligonucleotide fingerprinting of genomic DNA from oral isolates of four different Candida species other than C. albicans and atypical chlamydospore-positive isolates from human immunodeficiency virus (HIV)-positive individuals and AIDS patients was investigated as a means for differentiating between isolates within individual species. Oligonucleotides composed of simple repetitive sequence motifs, including (GACA)4, (GATA)4, (GGAT)4, (GTG)5, and (GT)8, all yielded fingerprints suitable for strain segregation of 8 C. tropicalis isolates, 12 Torulopsis (Candida) glabrata isolates, 8 atypical Candida isolates, and, except for (GATA)4, 2 C. krusei probe in turn and so generate several distinct DNA fingerprints of the same DNA sample. However, none of the probes yielded fingerprints suitable for strain segregation with three C. parapsilosis isolates. The (GATA)4 probe was also used to detect restriction fragment length polymorphisms among a genetically closely related group of atypical Candida isolates on primary isolation from an additional HIV-infected patient. These chlamydospore-positive atypical Candida isolates were sucrose positive, were of C. albicans serotype A, hybridized weakly with the C. albicans-specific mid-repeat sequence probe 27A, and yielded fingerprint profiles by random polymorphic DNA analysis that were distinct from those derived from C. albicans isolates. The C. stellatoidea ex-type strain NCPF 3108 was indistinguishable from the atypical Candida isolates in all these tests and also yielded an identical carbohydrate and nitrogen source assimilation profile by using the ID 32C yeast identification system.

AIDS-Related Opportunistic Infections↗
PubMed1993

Clinical comparisons of continuous venous oxygen saturation and hematocrit monitors in pediatric surgery.

Continuous venous oxygen saturation and hematocrit values are important parameters in assessing patient status while on cardiopulmonary bypass. Two devices used to measure continuous venous oxygen saturation while on cardiopulmonary bypass were compared to a control. The Bentley Oxysat meter and the Medtronic MX2 Oxygen Saturation and Hematocrit System were compared to the ABL500 blood gas monitor. The continuous hematocrit readings from the MX2 system were compared to spun hematocrits. Twenty-nine pediatric patients ranging from 2.3kg-43.3kg were randomly selected. In-line optical transmission cells used were 1/4" or 3/8" depending upon the patient's blood flow requirements. A total of 163 data points were analyzed at different blood flow rates, temperatures, and hematocrits. The venous oxygen saturation values obtained from the Oxysat and the MX2 devices correlated well with the ABL500 over the entire range of blood flows, temperatures, and hematocrits. All correlation coefficients were greater than 0.89. The correlation between the MX2 device and the spun hematocrit varied with temperature ranges. The correlation coefficient tended to decrease with decreasing temperature. We conclude that these devices are important adjuncts to bypass as long as their limitations are understood.

Blood Gas Analysis↗
PubMed1993

The Bicore pulmonary monitor. A device to assess the work of breathing while weaning from mechanical ventilation.

The Bicore CP-100 pulmonary monitor offers the advantage of continuous pulmonary monitoring at the bedside. Using an easily placed oesophageal balloon catheter and a flow transducer within the ventilator system, intrathoracic pressures, airway pressures and airway flow can be measured, and from these the Bicore calculates 25 other respiratory variables. The monitor screen displays real time waveforms of airway pressure, airway flow, oesophageal pressure and inspired tidal volume, and with these data it should be possible to determine more accurately when patients can be weaned from mechanical ventilation. It should also be possible to assess objectively the onset of respiratory fatigue and failure so that intervention can take place at an earlier stage. To assess the ease of use and potential benefit, the Bicore was used to calculate the work of breathing while weaning eight patients from mechanical ventilation in a spontaneous breathing mode. The pressure support ranged from 20 cmH2O, 10 cmH2O and 5 cmH2O, to a continuous positive airway pressure of 5 cmH2O, all with a positive end-expiratory pressure of 5 cmH2O, down to a single T-circuit with no positive airway pressure or end-expiratory pressure. The work of breathing while on a Veola Hamilton ventilator was found to be about the same, while receiving pressure support of 20 cmH2O compared to a continuous positive airway pressure of 5; the other forms of respiratory support increased the work of breathing significantly.

Humans↗
PubMed1993

Occupational health: a discipline out of focus.

This article first examines three areas of occupational health: the work of the International Commission on Radiological Protection (ICRP), the work on chemicals of the American Conference of Governmental Industrial Hygienists (ACGIH), and the International Labour Organization (ILO) Convention and Recommendation on Occupational Health Services. All three areas are criticized, using the notion of a "scientific strategy" which is the use of bodies of scientific knowledge and techniques in approaching occupational health. In the first two areas, it is contended that a misguided scientific strategy has been adopted which is a comment on the role of scientists in policy-making. In the third case, it is argued that the Convention and Recommendation emphasize the remedial aspects of occupational health to the detriment of the preventive side, a reflection of the undue influence of industrial medicine on occupational health. A proper approach to occupational health would make very different demands on science and would employ engineering techniques at the expense of the medical disciplines. As it is, occupational health is out of focus.

Canada↗
PubMed1993

Dopexamine hydrochloride maintains portal blood flow and attenuates hepatic ultrastructural changes in a porcine peritonitis model of multiple system organ failure.

Fifteen anesthetised pigs (25-30 kg) were divided into three equal groups, sham, dopexamine (D) (10 micrograms/kg/min), and placebo (P). Sepsis was induced by fecal peritonitis in the D and P groups and colloid was infused to try to maintain mean arterial blood pressure (MABP) at a constant value and the hemodynamics measured at baseline and hourly for 8 hr. There was an initial increase in MABP and systemic vascular resistance (SVR) in the P group but not the dopexamine (D) group. Cardiac output (CO) in the P group showed a small decline but increased in the D group. The portal blood flow (PVF) in the P group fell with MABP but increased in the D group as MABP fell. The sham group showed normal ultrastructure and cellular integrity. Occlusion of the hepatic sinusoids was similar in the D and P groups. There was a greater area of Kupffer cells and endothelial cells in the P group, suggesting a greater inflammatory reaction than was found in the D group. Ultrastructure and mitochondrial integrity was better maintained in the D group. Dopexamine hydrochloride infusion maintained CO, increased PVF, and attenuated hepatic ultrastructural changes compared to placebo in a porcine fecal peritonitis model of multisystem organ failure.

Animals↗
PubMed1992

Testis-/embryo-expressed genes are clustered in the mouse H-2K region.

The major histocompatibility complex (MHC) of the mouse is located on chromosome 17 in the distal inversion of the t complex. In addition to genes playing major roles in the immune response, it contains a diversity of genes. In humans, numerous diseases are known to be associated with the MHC loci. Moreover, at least three recessive embryonic t-lethal mutations have been mapped to the MHC. Here a molecular genetic approach was used to study the detailed genomic structure of 240 kilobases (kb) surrounding the H-2K gene and 150 kb of a partly homologous region located in the distal inversion of the t complex. Combined with previous findings, the H-2K region was found to contain an impressively high density of genes--12 transcription units in 240 kb. Surprisingly, virtually all of these genes are expressed in testis and/or embryos. The genomic organization of this region is contrasted with the 150 kb of the homologous area where only three genes and an endogenous retrovirus reside.

Animals↗
PubMed1992

Combination therapy with zidovudine and dideoxycytidine in patients with advanced human immunodeficiency virus infection. A phase I/II study.

OBJECTIVE: To evaluate the safety and immunologic and antiviral effects of combination therapy with zidovudine and dideoxycytidine (ddC) in patients with advanced human immunodeficiency virus type 1 (HIV) infection. DESIGN: A phase I/II open-label, dose-ranging study. SETTING: Two AIDS Clinical Trials Group units. PATIENTS: Patients (56) with advanced HIV disease. INTERVENTIONS: Patients were randomly assigned to one of three paired regimens of zidovudine and ddC. We evaluated six dosing regimens, each involving oral administration of the study drugs at 8-hour intervals. MEASUREMENTS: Pharmacokinetics, toxicity, CD4 counts, p24 antigenemia and clinical end points. MAIN RESULTS: The median follow-up period was 40.6 weeks (range, 0.3 to 70 weeks). Neither drug affected the pharmacokinetic profile of the other. Episodes of serious hematologic toxicity were infrequent, occurring in only 17.9% of patients, and did not differ among the regimens (P = 0.15). Severe sensory peripheral neuropathy occurred in two patients (one patient each in regimens 1 and 4). One patient receiving regimen 4 died. The mean maximal increase in CD4 counts exceeded 109 cells/mm3, and 69% of patients receiving combinations containing 300 or 600 mg of zidovudine daily had an increase in CD4 counts of 50 cells/mm3 or greater. Regimens containing 600 mg of zidovudine daily (regimens 2 and 5) were also more likely to result in persistent increases in CD4 counts above pretreatment values than were the two lowest dose regimens (P = 0.003). The decline in CD4 counts was more rapid, and the suppression of the p24 antigenemia was less rapid and less sustained in patients receiving the lowest zidovudine dose alone (regimen 6). The addition of ddC to regimen 6 (regimen 3) resulted in a slower decline in the CD4 counts (P = 0.06). CONCLUSIONS: Combination therapy with zidovudine and ddC at the doses tested was well tolerated and did not result in toxicity. A daily oral dose of 150 mg of zidovudine appeared to produce a suboptimal effect on p24 antigenemia and CD4 counts. Combination therapy with ddC and higher doses of zidovudine produced greater and more persistent effects in patients with advanced HIV infection compared with other study regimens and with the results of previous trials of zidovudine monotherapy.

Adult↗
PubMed1992

Metallic foreign bodies in the mouth or pharynx of horses: seven cases (1983-1989).

Seven horses with metallic foreign bodies in the mouth or pharynx were examined at the Colorado State University Veterinary Teaching Hospital from 1983 to 1989. The horses had variable clinical signs, such as purulent nasal discharge, swelling of the throatlatch area, and dyspnea. Most of the horses had clinical signs for more than 2 weeks, and had no or only temporary improvement with conservative medical treatment (antibiotics, nonsteroidal anti-inflammatory drugs). The definitive diagnostic test in all of the cases was radiography, which also aided in the plan for surgical removal of the foreign body. Once the foreign body was removed from each of the horses, their clinical signs resolved. Most of the foreign bodies were small pieces of wire, the sources of which could not be determined, but that may have been incorporated in baled hay.

Animals↗
PubMed1992

Detection of canine distemper virus in bone cells in the metaphyses of distemper-infected dogs.

In the light of recent evidence implicating canine distemper virus (CDV) as a possible etiologic agent in Paget's disease of bone, we thought that it would be of interest to examine distemper-infected bone in the natural host. Samples from the long bones, spleen, and bladder of four distemper-infected and three uninfected dogs were examined for the presence of CDV nucleocapsid and phosphoprotein genes and the measles virus (MV) nucleocapsid gene using the technique of in situ hybridization with radioactively labeled riboprobes. Two of the four distemper-infected dogs showed strongly positive hybridization with both of the CDV probes. The signal was present in marrow cells, in osteoblasts, in osteocytes, and particularly in osteoclasts. No hybridization was seen over the cartilage cells of the growth plate, and there was a clear line of demarcation at the point of invasion of osteoclasts and vascularization. The spleen and bladder samples from infected dogs also showed positive hybridization. There was no hybridization with the MV probe in any of the distemper-infected tissue. Samples from the uninfected dogs showed no evidence of hybridization with either the CDV or MV probes. These results show that CDV can infect bone cells of the natural host and provide further support for the theory that CDV may play a role in human Paget's disease of bone.

Animals↗
PubMed1992

Lymphocyte populations in the synovial membranes of dogs with rheumatoid arthritis.

Lymphocyte populations in the synovial membranes of dogs with canine rheumatoid arthritis (CRA) were investigated by immunohistochemical staining techniques. T-lymphocytes were the predominant cell type distributed throughout the supporting layer of the synovial membranes. B-lymphocytes expressing IgG were seen far more commonly than those expressing either IgA or IgM. Synovial membrane biopsies from normal and osteoarthritic joints did not have the marked cellular infiltrates seen in joints with CRA. The synovial immunohistopathological features in dogs with CRA are similar to those seen in human rheumatoid arthritis.

Animals↗
PubMed1992

Recombinant tissue-type plasminogen activator versus a novel dosing regimen of urokinase in acute pulmonary embolism: a randomized controlled multicenter trial.

Thrombolysis of acute pulmonary embolism can be accomplished more rapidly and safely with 100 mg of recombinant human tissue-type plasminogen activator (rt-PA) (Activase) than with a conventional dose of urokinase (Abbokinase) given as a 4,400-U/kg bolus dose, followed by 4,400 U/kg per h for 24 h. To determine the effects of a more concentrated urokinase dose administered over a shorter time course, this trial enrolled 90 patients with baseline perfusion lung scans and angiographically documented pulmonary embolism. They were randomized to receive either 100 mg/2 h of rt-PA or a novel dosing regimen of urokinase: 3 million U/2 h with the initial 1 million U given as a bolus injection over 10 min. Both drugs were delivered through a peripheral vein. To assess efficacy after initiation of therapy, repeat pulmonary angiograms at 2 h were performed in 87 patients and then graded in a blinded manner by a panel of six investigators. Of the 42 patients allocated to rt-PA therapy, 79% showed angiographic improvement at 2 h, compared with 67% of the 45 patients randomized to urokinase therapy (95% confidence interval for the difference in these proportions [rt-PA minus urokinase] is -6.6% to 30.4%; p = 0.11). The mean change in perfusion lung scans between baseline and 24 h was similar for both treatments. Three patients (two treated with rt-PA and one with urokinase) had an intracranial hemorrhage, which was fatal in one. The results indicate that a 2-h regimen of rt-PA and a new dosing regimen of urokinase exhibit similar efficacy and safety for treatment of acute pulmonary embolism.

Acute Disease↗
PubMed1992

Fluid balance in elderly patients following acute stroke.

We studied the relationship between plasma osmolality, arginine vasopressin (AVP), and fluid input in patients during the acute phase of a first stroke. Fifteen consecutive patients were studied (median age 79) and their blood sampled on days 0, 1, 2, 3, 7 and 14. Plasma osmolality was related to fluid input over days 0-3 (p = 0.0013) and AVP over 14 days (p less than 0.001). Patients with a poor outcome had higher AVP concentrations (p = 0.02). Those on intravenous fluids received a higher volume (p less than 0.01) and had a lower plasma osmolality (p = 0.04). The results of this preliminary study indicate that a standard regime for fluid input is inappropriate.

Aged↗
PubMed1992

Influence of age on the relation between heart rate variability, left ventricular ejection fraction, frequency of ventricular extrasystoles, and sudden death after myocardial infarction.

AIMS: To examine the influence of age on the prediction of sudden death after acute myocardial infarction based on heart rate variability (HRv), left ventricular ejection fraction (LVEF), and the frequency of ventricular extrasystoles. BACKGROUND: Autonomic and left ventricular function and the frequency of ventricular extrasystoles change with age but the influence of age on the prediction of sudden death from these variables has not been examined. METHODS: The 477 patients who had been through an early postinfarction risk stratification protocol and followed up for a mean of 790 days were dichotomised at 60 years of age. RESULTS: Sudden deaths occurred with similar frequency in both age groups (12 (4.7%) of the 256 patients aged < 60 years and seven (3.2%) of the 221 older patients). Sudden death, however, accounted for 52% of all deaths in the young group but only 18.4% of all deaths in the older group (p < 0.01). An HRv index of < 20 units combined with an average of more than 10 ventricular extrasystoles an hour on Holter monitoring (VE10) had a sensitivity of 50%, a positive predictive accuracy of 33%, and a risk ratio of 18 in the young group (p < 0.001) but was not significantly predictive in older patients. The situation was similar when the combination of an LVEF < 40% with VE10 was considered. This combination had a sensitivity of 44%, positive predictive accuracy of 36.4%, and a risk ratio of 16.1 in young patients (p < 0.001), but was not significantly predictive in older patients. The combination of VE10 with either LVEF < 40% or HRv < 20 units gave a sensitivity of 75%, positive predictive accuracy of 30%, and a risk ratio of 30 in young patients (p < 0.001), but the relation between this combination and sudden death in older patients was not statistically significant. CONCLUSION: In postinfarction patients aged < 60 sudden death was a more predominant mode of death and was more reliably predicted from a depressed HRv index, an LVEF < 40%, and VE10 than in older postinfarction patients. These findings may have important implications for post-infarction risk stratification and management.

Age Factors↗
PubMed1992

The dependency of oxygen consumption on oxygen delivery in critically ill postoperative patients is mimicked by variations in sedation.

The finding of a dependence of oxygen consumption on oxygen delivery in critically ill patients has encouraged interventions to increase oxygen delivery index (DO2I) to overcome tissue hypoxia. In individuals other factors may influence oxygen consumption index (VO2I) and DO2I and may cause an apparently dependent relationship. We studied the effects of sedation and temperature on the VO2I/DO2I relationship in 13 perioperative patients. Pooled data showed significant correlations between VO2I and DO2I (r greater than 0.6, p less than 0.05) but also between VO2I and sedation score (r greater than 0.7, p less than 0.05), but not VO2I and temperature (r less than 0.5). When VO2I was standardized for the effects of sedation score (SS), the relationship between VO2I and DO2I was lost (r less than 0.5). Seven of 13 patients had significant (p less than 0.05) correlations between VO2I and SS and six of 13 between VO2I and DO2I; when standardized for the effect of varying sedation, no relationships were significant. When interpreting oxygen transport data from critically ill patients, the effects of sedation but not temperature must be taken into account; otherwise a false impression of a dependent relationship between VO2I and DO2I may cause unnecessary treatment.

Biological Transport↗
PubMed1992

Lassa fever encephalopathy: clinical and laboratory findings.

Clinical and laboratory findings are reported in nine patients who developed acute encephalopathy during the course of Lassa fever. The encephalopathy manifested 3-17 days after disease onset with confusion, followed rapidly by tremor (seven patients), grand mal convulsions (seven), abnormal posturing (three) and coma (eight); focal neurological signs and evidence of raised intracranial pressure were not seen. Eight patients died, most commonly from respiratory arrest following a protracted fit. Development of encephalopathy did not correlate with the presence of virus in cerebrospinal fluid (CSF), nor with virus antibodies in CSF and/or serum; thus, neither direct cytopathic nor immune-mediated mechanisms seem to be involved in its pathogenesis.

Adolescent↗