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Biomedical subjects

D Marshall

Publications and source records attributed to D Marshall.

At least 19 recordsLinked to original sources
PubMed1992

Contact sensing in Candida albicans: a possible aid to epithelial penetration.

Hyphal development in the dimorphic pathogenic fungus Candida albicans is thought to facilitate the primary invasion of surface epithelia during superficial infections. When mycelia were grown on Nuclepore membrane filters that were placed over serum-containing agar, the hyphae grew over the membrane surface and through the pores thereby crossing to the other side of the membrane. Hyphae that did not contact the lip of a pore did not enter it. The response was likely to be due to contact guidance (thigmotropism) and not chemotropism towards the nutrients since hyphae growing on the underside of the membrane also entered the pores then grew away from the underlying nutrient agar. The response therefore seems to be due to sensation of the substrate topography, and tropic movement in relation to changes in contour. This behaviour may enable the hyphae to penetrate epithelia at microscopic wound sites, membrane invaginations and other foci where the integrity of the epithelium is weak.

Candida albicans↗
PubMed1992

Vascular catheter-associated fungemia in patients with cancer: analysis of 155 episodes.

We reviewed all 155 episodes of central venous catheter-associated fungemia among inpatients at the National Cancer Institute during a 10-year period. Candida species accounted for 98% of episodes. Fungemia was documented by culture of blood drawn through catheters in 50% of cases and by culture of both catheter-drawn and peripheral blood in 39%; mortality and the rate of dissemination were similar for these two groups. Four management strategies were used: catheter removal, antifungal therapy (with amphotericin B), both, or neither; indications for the use of both modes of treatment included fever, neutropenia, long-term indwelling catheterization, positive cultures of both catheter-drawn and peripheral blood, isolation of Candida tropicalis, and fungal isolation from two or more blood cultures. Disseminated fungal infection was documented in 82% of cases with these features but also in 35% of the less severe cases treated only with catheter removal. In addition, nine (82%) of 11 cases managed only with antifungal therapy had a negative outcome (either death from disseminated infection or the recurrence of fevers and/or fungemia), a finding suggesting that intravascular catheters should be removed in fungemia. Virtually all cases of catheter-associated fungemia in patients with cancer are clinically significant and require prompt therapy with amphotericin B.

Adolescent↗
PubMed1992

Patterns of infection in patients with aplastic anemia and the emergence of Aspergillus as a major cause of death.

Patterns of infection were studied in 150 patients with aplastic anemia who were admitted to the Clinical Hematology Branch, National Institutes of Health, between January 1978 and December 1989 for immunosuppressive therapy. Sixty percent of the patients were males, 71% were white, their mean age was 33.6 years (median, 27.5; range, 1-75), and 83% had severe aplastic anemia. One hundred three patients developed 1 or more febrile episodes during the study period. The risk factors for developing a febrile episode included a low Absolute Neutrophil Count (ANC) and Absolute Monocyte Count (AMC) at admission and the presence of an indwelling central venous catheter (Hickman-Broviack or Port-A-Cath). A total of 289 febrile events were studied, including unexplained fever (FUO) in 89 (31%), microbiologically documented infection (MBDI) in 137 (47%), and clinically documented infection (CDI) in 63 patients (22%). Compared to documented infections (MBDI) or CDI), FUO events were associated with a higher frequency of rigors, signs and symptoms of serum sickness, and treatment regimens known to cause fevers. None of the FUO events had a fatal outcome, even if the antibiotic therapy was discontinued before day 7. Among CDI events, bacteria were the most commonly defined etiologic agent (67%), followed by fungi (23%), viruses (7%), and parasites (3%). The patterns of bacterial infections in patients with aplastic anemia were similar to those observed in patients with cancer-related neutropenia. Twenty-one patients (15%) developed invasive fungal infections (aspergillus, 11; candida, 7; and both, 3), which were fatal in 19 (90%). Fungal infections accounted for 30% of the secondary infectious events and for 55% of fatal infectious events. The only identifiable risk factors for developing a fungal infection were the degree of neutropenia and monocytopenia at initial admission or final evaluation. Invasive pulmonary aspergillosis developed despite empirical amphotericin B therapy and was associated with a high incidence of fatal pulmonary hemorrhage (10 of 13 patients [77%]). Infection was responsible for 36 (62%) of the deaths observed during the study period and hemorrhage alone for 4 (7%). However, 20 of the patients who died of infection had concomitant hemorrhage. No significant drop in ANC, AMC, or platelet count could be demonstrated during a fatal infectious event as compared to a nonfatal infectious event. Invasive fungal infections, predominantly with aspergillus and candida, emerged in our study as the major causes of mortality in patients with aplastic anemia. Without bone marrow recovery the prognosis associated with invasive mycoses was grave.

Age Factors↗
PubMed1992

A prospective randomized trial comparing the infectious and noninfectious complications of an externalized catheter versus a subcutaneously implanted device in cancer patients.

PURPOSE: To compare the frequency of infectious episodes or other problems occurring with an externalized catheter (Hickman) versus a subcutaneously implanted device (Port-a-Cath, Pharmacia, Piscataway, NJ) in cancer patients, we performed a prospective, randomized study in 100 cancer patients (age range, 5 to 74 years). PATIENTS AND METHODS: Patients who were chemotherapy candidates and required an indwelling catheter were monitored prospectively and evaluated during the 180 days after the insertion of the catheter and again at time of study closure. The frequency of catheter use, reason for access, and any problems that might have been related to catheter use were noted. All data were collected prospectively and included the patient's age, sex, underlying malignancy, temperature, and leukocyte and absolute granulocyte counts at the time of catheter insertion and when complications occurred. The time to and reason for removal of the catheter, as well as any intercurrent infectious or mechanical problems, were also determined. RESULTS: Most of the infections that occurred were caused by gram-positive organisms, especially staphylococci or streptococci. A total of 22 complications (11 in each group) resulted in removal of the central line. Only one infection in the Hickman catheter group and four in the Port-a-Cath group led to removal of the central line. All other infectious episodes were successfully treated without removal of the catheters. The mean device life was 230 days for the Hickman catheter and 318 days for the Port-a-Cath (not significant). CONCLUSION: There were no differences between the two study groups regarding incidence of documented infections or mechanical or thrombotic complications.

Adolescent↗
PubMed1992

MRE enteropathy.

Explore the source record for details and available documents.

Adult↗
PubMed1991

Doxazosin in the treatment of essential hypertension in general medical practice in Latin America.

This Latin American study assessed in the general practice setting the efficacy and tolerance of once-daily doxazosin in the treatment of mild or moderate essential hypertension (sitting diastolic blood pressure, 95 to 115 mm Hg). Patients (n = 220) were treated with doxazosin for 12 weeks as monotherapy or in combination with other antihypertensive agents. At the final visit, doxazosin produced a mean change in sitting systolic/diastolic blood pressure of -18.4/-14.4 mm Hg, at a mean daily dose of 4.3 mg. One hundred sixty-three (77.6%) of the 210 evaluable patients were considered a therapeutic success. Lipid analyses identified a statistically significant (p = 0.02) reduction in total serum cholesterol (4.85%) and an overall decrease in triglyceride levels (5.12%). According to the Framingham Heart Study equation, doxazosin produced a highly significant (p less than 0.001) 20% reduction in the calculated probability of developing coronary heart disease in 10 years. Of the 220 patients evaluated, 54 (24.5%) reported side effects that were considered related to treatment. Ten (4.5%) patients reported side effects unrelated to treatment and 37 (16.8%) reported events of unknown relationship. Most side effects were mild or moderate and were tolerated or disappeared with continued treatment. Nine patients (4.1%) were discontinued from therapy and in 13 (5.9%) the dose was reduced. The most prevalent side effects were headache and dizziness. The investigator's overall assessment of antihypertensive efficacy was excellent or good for 176 patients (80.4%); tolerance was considered excellent or good in 193 patients (88.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗
PubMed1991

Bacterial infections in human immunodeficiency virus type 1-infected children: the impact of central venous catheters and antiretroviral agents.

We conducted a retrospective study to analyze the impact of central venous catheters (CVCs) and antiretroviral therapy on the frequency and the patterns of bacterial infections in children infected with human immunodeficiency virus during a 3-year period. Among 204 bacterial infections other than otitis media reviewed, soft tissue infection (n = 69), bacteremia (n = 57), pneumonia (n = 27) and sinusitis (n = 27) were encountered most frequently. Catheter-related staphylococcal infection was the most common infection in children with CVCs, particularly in those who were less than 6 years old. In children without CVCs, Streptococcus pneumoniae was the most frequent organism. Younger children had more CVC-related infections whereas children with lower CD4 counts had more CVC-related and CVC-unrelated infections. A lower frequency of CVC-unrelated infections was detected in patients who received antiretroviral therapy, especially those receiving a continuous infusion of zidovudine. These data suggest that increased frequency and altered patterns of bacterial infections are associated with the use of CVCs in these patients, but antiretroviral therapy may reduce the frequency of CVC-unrelated infections.

Adolescent↗
PubMed1991

Dogs as sentinels for Lyme disease in Massachusetts.

BACKGROUND: An investigation of the relationship between incident human cases of Lyme disease and seroprevalence of antibodies to B. burgdorferi in dogs was undertaken in order to determine whether dogs might serve as sentinels for Lyme disease. METHODS: 3011 canine serum samples were analyzed by ELISA for antibody to B. burgdorferi. Records of incident human cases of Lyme disease were obtained from the Massachusetts Department of Public Health. RESULTS: Regression analyses of the relationship between the log10 (mean incidence in people 1985-1989) and canine seroprevalence from July 1988-August 1989 revealed that canine seroprevalence was highly predictive of incidence (R2 = 0.86, p less than .0001). A logistic regression model that incorporates the altitude of the town where each dog was resident, the date of sampling, and information on each dog's age, sex, and breed adequately explained the risk of canine seropositivity. Dogs resident at altitudes less than 200 feet, of sporting or large mixed breeds, and greater than two years of age were five times, four times, and almost three times more likely, respectively, to exhibit seropositivity than were other dogs. CONCLUSIONS: Estimates of the prevalence of antibody to B. burgdorferi in dog populations offers a sensitive, reliable, and convenient measure of the potential risk to people of B. burgdorferi in the environment. Risk factors for canine seropositivity may directly or indirectly illuminate certain aspects of the epidemiology of human Lyme disease.

Age Factors↗
PubMed1991

Amphotericin B vs high-dose ketoconazole for empirical antifungal therapy among febrile, granulocytopenic cancer patients. A prospective, randomized study.

We compared high-dose ketoconazole (800 mg/kg per day, orally) with amphotericin B (0.5 mg/kg per day, intravenously) for empirical antifungal therapy in a prospective, randomized study of persistently or recurrently febrile granulocytopenic cancer patients. Among 97 patients eligible for empirical antifungal therapy, 20 (21%) of these patients were ineligible for randomization to ketoconazole treatment because of their inability to tolerate oral medications. Among 72 patients eligible for randomization, 64 were assessable (32 in each arm of the study). Five of six patients with proved fungal infections who were randomized to receive ketoconazole treatment required crossover to amphotericin B treatment because of progressive infection. The conditions of three of these five patients improved after receiving amphotericin B. The frequency of transaminase elevation was higher in those receiving ketoconazole, while the frequency of azotemia was higher in those receiving amphotericin B. Bioavailability of ketoconazole was unpredictable. Amphotericin B remains the drug of choice for empirical antifungal therapy in granulocytopenic patients; whereas, lack of a parenteral formulation, ineffectiveness against proved mycoses, and unreliable bioavailability preclude high-dose ketoconazole from being an appropriate compound for this purpose.

Adult↗
PubMed1990

The use of stable isotopes and gas chromatography/mass spectrometry in the identification of steroid metabolites in the equine.

Stable isotope gas chromatography/mass spectrometry has been used successfully in the elucidation of structures of urinary steroid metabolites in the horse and in the identification of metabolites isolated from in vivo perfusion and in vitro incubation studies using equine tissue preparations. Deuterium-labeled steroids, testosterone, dehydroepiandrosterone, and 5-androstene-3 beta,17 beta-diol have been synthesized by base-catalyzed isotope exchange methods and the products characterized by gas chromatography/mass spectrometry. [16,16(-2)H2]Dehydroepiandrosterone (plus radiolabeled dehydroepiandrosterone) was perfused into a testicular artery of a pony stallion and was shown to be metabolized into 2H2-labeled testosterone, 4-androstenedione, isomers of 5-androstene-3,17-diol, 19-hydroxytestosterone, and 19-hydroxy-4-androstenedione. In further studies, equine testicular minces have been incubated with 2H2-labeled and radiolabeled dehydroepiandrosterone and 5-androstene-3 beta, 17 beta-diol. The metabolites, whose identity was confirmed by stable isotope gas chromatography/mass spectrometry, proved the interconversion of the two substrates, as well as formation of testosterone and 4-androstenedione. The aromatization of dehydroepiandrosterone was also confirmed, together with the formation of an isomer of 5(10)-estrene-3,17-diol from both substrates showing 19-demethylation without concomitant aromatization. In studies of the feto-placental unit, the allantochorion was shown to aromatize [2H5]testosterone to [2H4]estradiol, the loss of one 2H from the substrate being consistent with aromatization of the A ring. The formation of 6-hydroxyestradiol was also confirmed in this study. The same technique has been valuable in determining the structure of two metabolites of nandrolone isolated from horse urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Allantois↗
PubMed1990

Some of the factors involved in the Sarvazyan method for recording ultrasound field distributions with special reference to the application of ultrasound in physiotherapy.

The mapping of ultrasound fields using the dye paper method is described. The mode of action by which the dye concentration is increased has been investigated. Microbubbles on the paper surface and microstreaming of dye solution seem to be essential features of the mapping method. The streaming is thought to inhibit the formation of a dye depletion layer near the paper to an extent dependent on local sound intensity A linear relation between streaming velocity and intensity is derived.

Coloring Agents↗
PubMed1990

Role of cardiac work in regulating myocardial biochemical characteristics.

The purpose of this study was to determine the extent to which functional demand regulates the biochemical character and enzyme capacities of the rat myocardium. Hearts from donor rats were heterotopically transplanted onto the abdominal aorta and inferior vena cava of isogenic recipients. The procedure results in a perfused but nonpumping heart that has a reduced heart rate (HR) and performs essentially no stroke work (SW). After 30 days, metabolic enzyme activities (phosphorylase, 6-phosphofructokinase, citrate synthase, and 3-hydroxyacyl-CoA dehydrogenase) were significantly lower (40-60%) in the nonworking heart. Specific sarcoplasmic reticulum Ca2(+)-adenosinetriphosphatase (ATPase) activity was unchanged, but activity per gram of heart was 41% lower. Myosin isozymes were 58% V1, 21% V2, and 21% V3 in the nonworking heart compared with 100% V1 in the working heart. Myosin and myofibrillar ATPase activities each decreased by 28%. These findings suggest that both HR and SW play major and specific roles in regulating myocardial biochemical capacities and determining the myosin phenotype.

Animals↗
PubMed1990

Bovine serological response to a recombinant BPV-1 major capsid protein vaccine.

Four of five groups of Holestine by Angus calves (5 calves/group) were immunized with different formulations of a recombinant BPV-1 DNA vaccine using a BPV-1 major capsid:B-galactosidase fusion protein as the immunogen. Group 5 was not vaccinated. Vaccinated calves received the vaccine on days 0 and 21 of the trial, and calves from all five groups were challenged intradermally with 10(10) BPV-1 particles at each of two different sites on day 56. All calves were bled on days 3, 24, 55, 77, and 104 of the trial, and the sera were tested for reactivity with intact and disrupted BPV-1 particles by ELISA. At the time of challenge with BPV-1 virions (day 56), 19 of 20 vaccinated calves were seropositive for disrupted BPV-1 particles; sera from 3 of 20 calves reacted with intact BPV-1 virions. By day 77, 11 of 19 vaccinated calves had developed antibody titers to intact BPV-1 virions; only 1 calf in group 5 developed antibodies (transiently) against BPV-1 capsid epitopes. After challenge, 24 of 25 calves from the five groups developed intradermal fibromas, the biological end point of this study. Fibromas appeared to increase in size in group 5 (unvaccinated, inoculated controls), whereas most tumors from the four vaccinated groups (1-4) stabilized or decreased in size. Although the calves developed fibromas, 90% of calves (in groups 1-4) developed antibodies against disrupted BPV-1 capsid proteins whereas 58% developed antibodies that reacted with intact virions. The immunologic response of vaccinated calves to intact and disrupted BPV-1 particles appeared to be determined in large part by the various formulations of the vaccine, particularly the adjuvant.

Animals↗