Bayesian forecasting of APTT response to continuously infused heparin with and without warfarin administration.
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Adult↗
Biomedical subjects
R Floyd
Publications and source records attributed to R Floyd.
Recovery of human immunodeficiency virus and detection of p24 antigen in bronchoalveolar lavage fluid from adult patients with AIDS.
Published reports indicate that HIV is recovered from BAL fluid of patients with AIDS who have LIP but not with other AIDS-related pulmonary disease. Our experience has been different. Ten BAL specimens from nine patients with AIDS were cultured directly in peripheral blood mononuclear cells, and all ten cultures were positive for HIV as indicated by examination of the culture supernatant by reverse transcriptase assay and enzyme immunoassay for HIV antigen. Five of the specimens were also positive for Pneumocystis carinii, and other pulmonary diagnoses included histoplasmosis, lymphoma, Kaposi's sarcoma, and aspiration pneumonia. Five additional BAL specimens were cultured after freezing at -70 degrees C, but only two were culture-positive for HIV (p = 0.022; FET). This study indicates that HIV can be recovered from the BAL fluid in most patients with AIDS, unrelated to the type of pulmonary disease. In contrast to cultures, HIV antigen was detected in the BAL fluid of only one patient, and that patient had LIP with noncaseating granulomas. Therefore, HIV culture is not useful in the diagnosis of LIP, but HIV antigen detection should be studied further. All BAL fluids should be considered potentially infectious.
Acquired Immunodeficiency Syndrome↗
Gentamicin-resistance plasmids in an intensive care unit.
To better understand the role of plasmids and their importance in the endemic antibiotic resistance of Enterobacteriaceae, we began a prospective study of our combined medical intensive care/coronary care unit. An initial culture survey of the patients, ward staff, and environment was followed by a prospective sampling of 139 consecutive new admissions at the time of admission to the unit, and at regular intervals thereafter for the remainder of their stay. All cultures were planted on agar-containing gentamicin. Of the 147 patients studied, 12 (8.2%) were colonized with 20 strains of gentamicin-resistant gram-negative bacilli (GRGNB) at 29 sites. An additional four GRGNB were isolated from the environment. Of the 24 GRGNB strains, 7 (29%) Enterobacteriaceae carried plasmids shown to carry the gentamicin-resistance determinant. Plasmids were further characterized by restriction endonuclease digestion profiles of plasmid DNA purified from E. coli C600 transconjugants or transformants. A 93 kb plasmid introduced to the unit by a Serratia liquefaciens colonizing a patient transferred from another area in the hospital was identical to 93 kb plasmids carried by a C. amalonaticus and an E. aerogenes subsequently colonizing another patient on the unit. A 60 kb plasmid, first isolated from a S. marcescens colonizing a sink drain was later isolated from an E. cloacae colonizing a patient. Our results indicate that spread of specific R-plasmids may be one mechanism for dissemination of antibiotic resistance on our MICU/CCU.
Drug Resistance, Microbial↗
Prevalence of colonization with antibiotic resistant gram-negative bacilli in a nursing home care unit: the importance of cross-colonization as documented by plasmid analysis.
A prevalence study was carried out on a 100-bed Veterans Administration nursing home care unit to determine the extent of colonization with gentamicin-resistant gram-negative bacilli (GRGNB). Hand cultures of 12 employees and 17 environmental cultures were negative. Twenty-six of 86 (30%) patients were colonized with 49 GRGNB. Sixteen patients (19%) had urinary colonization. Multivariate analysis revealed significant associations between rectal or perineal colonization (P less than 0.01), and the presence of a urinary device (82% condom catheters) (P less than 0.05), with urinary colonization. The most common isolates were Providencia stuartii (20), Escherichia coli (nine) and Klebsiella pneumoniae (nine). Twenty-six of 49 isolates carried plasmids. Restriction endonuclease digestion of plasmid DNA was performed for 21. Cross-colonization, as defined by the presence of the identical species with the identical restriction endonuclease digestion profile of purified plasmid DNA found in different patients, was observed for eight of 21 (38%) strains. All were geographically clustered. No strains could transfer gentamicin-resistance by conjugation and only two plasmids could transform our E coli recipient to gentamicin resistance. One E coli plasmid was identical to two Citrobacter freundii plasmids and a P stuartii plasmid isolated from three different patients. This 105 kb plasmid is conjugative and encodes resistance to ampicillin, carbenicillin, tetracycline, and sulfonamides. Thus, 57% of strains were cross-colonizing or contained identical R-plasmids. Southern hybridization using a 1 kb TEM-1 gene probe demonstrated sequences homologous to this probe in five of five nursing home plasmids examined.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
One-day treatment of vulvovaginal candidiasis with a 500-mg clotrimazole vaginal tablet compared with a three-day regimen of two 100-mg vaginal tablets daily.
In a randomized, double-blind trial, the efficacy and safety of a new single-dose clotrimazole vaginal tablet were compared with that of three-day clotrimazole therapy. Forty-two patients with clinically and mycologically confirmed vulvo-vaginal candidiasis received either one 500-mg clotrimazole tablet for one day or two 100-mg tablets daily for three days. Follow-up visits were performed approximately one week and one month after treatment. Thirty-six patients were evaluated for drug efficacy. There was no significant difference in clinical and mycological responses to the two regimens (P = 1.00, Fisher's exact test). At the final visit, 16 (89%) of the 18 patients receiving one-day treatment showed mycological and clinical clearance of infection, as compared to 15 (83%) of the 18 patients receiving three-day therapy. One patient in the three-day treatment group presented moderate edema of the vulva which was judged to be remotely related to treatment. The findings indicate that a single 500-mg tablet of clotrimazole is as effective and safe in the treatment of vulvovaginal candidiasis as a three-day course of 200 mg/day.
Adult↗
Therapeutic results obtained in vaginal mycoses after single-dose treatment with 500 mg clotrimazole vaginal tablets.
A multicenter, double-blind study of 103 patients with clinically and mycologically documented vulvovaginal candidiasis compared single-dose treatment with a 500 mg clotrimazole vaginal tablet to 3-day treatment with two 100 mg clotrimazole vaginal tablets administered daily. Patients were examined 5 to 10 days (visit 2) and at least 27 days (visit 3) post treatment. At visit 2, mycologic and clinical examinations were negative in 43 of 48 efficacy-evaluable patients receiving clotrimazole, 500 mg (90%), versus 42 of 47 efficacy-evaluable patients receiving clotrimazole, 200 mg (89%). Similarly, at visit 3, 75% of patients receiving clotrimazole, 500 mg, had treatment success versus 72% receiving clotrimazole, 200 mg. There were no significant intergroup treatment differences, indicating that single-dose treatment with clotrimazole, 500 mg, is equipotent to the multidose regimen.
Adolescent↗
Type II collagen mediated autoimmune middle ear disease: eustachian tube disease, otitis media with effusion and tympanosclerosis.
Intact Eustachian tube and tympanic cavity functions are essential for normal middle ear physiology. Type II collagen is an essential component of ear tissue. Autoimmune response to this type II collagen produces sensorineural hearing loss, vestibular dysfunction, endolymphatic hydrops, otospongiosis-like lesions, Eustachian tube inflammation and Eustachian tube chondritis. In addition, these autoimmune responses occasionally produce otitis media with effusion (not infectious). Tympanosclerosis, which is a frequent sequelae of otitis media with effusions, was also induced by type II collagen immunization together with surgical incision of the tympanic membrane. The exact mechanisms of this type II collagen autoimmune mediated middle ear disease are not clear. However, the animals thus induced have higher antibody titers and cell mediated immune responses to type II collagen. The tympanic membrane showing tympanosclerosis also had C3 and Ig deposits. All the animals with otitis media with effusion induced by type II collagen immunization also had Eustachian tube disease. This could be due to a malfunction of the Eustachian tube. Thus, this model might provide a rational approach for the study of otitis media with effusion associated with vasculitis. Further studies are needed to elucidate the immunologic mechanism involved in the pathogenesis of otitis media with effusion.
Animals↗
Type II collagen induced autoimmune salpingitis in the rat.
Previous studies showed type II collagen induced autoimmune salpingitis in Wistar rats. In this study we increased the number of animals and investigated whether or not type II collagen induced salpingitis is transferable by immune sera. Histopathological observations of salpingitis in the serum transferred rats were similar to those observed in the immunized rats but the degree of otopathological changes was less than that of immunized rats. Electronmicroscopic findings indicate an increased permeability in the capillaries and intercellular space and cellular infiltration in the submucosa of the immunized rats.
Animals↗
Immunologic testing of certain ear diseases.
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Antibody-Dependent Cell Cytotoxicity↗
Impairment of cell-mediated immunity functions by dietary zinc deficiency in mice.
Several immunologic features were analyzed in mice on a zinc-deficient diet [Zn(-)], in mice pair-fed a diet containing zinc [Zn(+)], in mice fed a Zn(+) diet ad lib, and in mice fed laboratory chow ad lib. When placed on a Zn(-) diet, 6- to 8-week-old A/Jax, C57BL/Ks, and CBA/H mice showed loss of body weight, low lymphoid tissue weight, and profound involution of the thymus within 4-8 weeks after initiation of the regimen. Approximately 50% of the mice on the Zn(-) diet developed severe acrodermatitis enteropathica (lesions on tail and paws) and diarrhea. Pair-fed mice on the Zn(+) diet did not show any of these symptoms. Mice on the Zn(-) diet showed the following immune deficiencies: (i) depressed plaque-forming cells against sheep erythrocytes after in vivo immunization; (ii) depressed T killer cell activity against EL-4 tumor cells after in vivo immunization; and (iii) low natural killer cell activity. However, antibody-dependent cell-mediated cytotoxicity against chicken erythrocytes was normal in the mice on the Zn(-) diet. Deficiency of T killer cell activity was not observed when immunization with EL-4 allogeneic lymphoma cells was carried out in vitro. Progressive loss of relative and absolute number of Thy 1.2+ cells and a proportionate relative increase in cells bearing Fc receptors was seen in spleen and lymph nodes of Zn(-) animals. It appears that zinc is an essential element for maintenance of normal T cell and other immune functions in vivo.
Animals↗
Viral aggregation: buffer effects in the aggregation of poliovirus and reovirus at low and high pH.
The effects of the buffer employed in maintaining a given pH value were tested on the aggregation of two viruses, poliovirus and reovirus. Poliovirus was found to aggregate at pH values of 6 and below, but not at pH 7 or above, except in borate buffer. Reovirus aggregated at pH 4 and below, but was found to aggregate only in acetate or tris(hydroxymethyl)aminomethane-citrate buffers at pH 5. Other buffers tested for aggregation of reovirus at pH 5 (succinate, citrate, and phosphate-citrate) induced little aggregation. No significant aggregation was found for reovirus at pH 6 and above. For both viruses, the most effective aggregation was induced by buffers having a substantial monovalently charged anionic component, such as acetate at pH 5 and 6 or citrate at pH 3. Cationic buffers at low pH, such as glycine, were generally weaker in aggregating ability than anionic buffers at the same pH. These results, when correlated with the isoelectric point of the viruses (poliovirus at pH 8.2; reovirus at pH 3.9) indicated that both viruses aggregated strongly when their overall charge was positive, but only under certain circumstances when their overall charge was negative. Although reovirus aggregated massively at its isoelectric point, poliovirus remained dispersed at its isoelectric point. The conclusion can be drawn that those pH and buffer conditions which induced aggregation of one virus do not necessarily induce it in another.
Acetates↗
Viral aggregation: mixed suspensions of poliovirus and reovirus.
The aggregation of mixtures of two dissimilar viruses, poliovirus I (Mahoney) and reovirus III (Dearing), was followed by electron microscopy under conditions known to induce either aggregation or dispersion of each virus separately. Neither virus aggregated at pH 7 in an appropriate buffer, and no mixed aggregates were formed. Under conditions of lowered ionic strength (by dilution into distilled water) poliovirus became aggregated, whereas reovirus did not, and again no mixed aggregates were formed. At pH 6, however, poliovirus again aggregated and, although reovirus did not, it attached to poliovirus aggregates. Thus, some inducement toward aggregation was necessary to cause formation of mixed aggregates. This inducement probably took the form of a reduction of the ionic double layer surrounding the particles, which is known to occur at low pH. At pH 5 and below both viruses aggregated severely, and large mixed aggregates were formed. These mixed aggregates could be broken up by neutralization of the suspension, although small aggregates of poliovirus remained. Reovirus showed a marked tendency to attach to large clumps of poliovirus, but the reverse tendency was not observed. The results indicate that mixed aggregates may be of significance in the isolation of viruses from water or wastewater.
Acetates↗
Viral aggregation: quantitation and kinetics of the aggregation of poliovirus and reovirus.
The aggregation of poliovirus and reovirus was followed in buffers at various pH values by means of a single particle analysis (SPA) test. The SPA test used here was modified from the original test reported earlier to prevent disaggregation of virus clumps from invalidating the results. The modified SPA test demonstrated that the efficiency of aggregation, which is a measure of the percentage of collisions which are effective in producing an aggregate, may vary widely depending on the conditions in which the virus is placed. The modified SPA test was also used to demonstrate that the kinetic features of viral aggregation follow the classical laws of colloid particle aggregation, which in turn are solely dependent upon diffusion of the particles as caused by brownian motion.
Adsorption↗
Viral aggregation: effects of salts on the aggregation of poliovirus and reovirus at low pH.
As a first step toward the understanding of virus particle interactions in water, we have used the modified single particle analysis test to follow the aggregation of poliovirus and reovirus as induced by low pH in suspensions containing varying amounts of dissolved salts. Salts composed of mono-, di-, and trivalent cations and mono- and divalent anions were tested for their ability to reduce or increase the aggregation of these viruses in relation to that obtained by low pH alone. Mono- and divalent cations in concentrations covering those in natural waters were generally found to cause a decrease in aggregation, with the divalent cations having a much greater effectiveness than the monovalent cations. Trivalent ions (Al3+), in micromolar concentrations, were found to cause aggregation over that at low pH alone. Anions, whether monovalent or divalent, had little ability to produce inhibition of viral aggregation, and thus the overall effects were due almost exclusively to the cation. This was true regardless of whether the overall charge on the virus particle was positive or negative, as determined by the relation between the isoelectric point and the pH at which the tests were carried out. Thus, whereas virus particles conform to classical colloid theory in many respects, there are specific exceptions which must be taken into account in the design of any experiment in which viral aggregation is a factor.
Adsorption↗
Aggregation of poliovirus and reovirus by dilution in water.
Poliovirus and reovirus were found to aggregate into clumps of up to several hundred particles when diluted 10-fold into distilled water from a stock preparation of minimal aggregation in 0.05 M phosphate buffer, pH 7.2, plus 22 to 30% sucrose. Reovirus was also found to aggregate when diluted into phosphate-buffered saline. The aggregation was concentration dependent and did not occur when either virus was diluted into water 100-fold or greater. The aggregation of poliovirus was reversible by further addition of saline and produced a dispersed preparation of virus. Reovirus aggregation was not reversible. Both viruses aggregated when diluted into buffers at pH 5 and 3, and poliovirus aggregated at pH 6, and this aggregation of both viruses was reversible when returned to pH 7. Aggregation did not occur at alkaline pH values. Aggregation at low pH could be caused aggregation of either virus at pH 7. Calcium ions, however, were found to aggregate both viruses at a concentration of 0.01 M.
Calcium↗
Initial fast reaction of bromine on reovirus in turbulent flowing water.
An apparatus is described for precise observation of the kinetics of the initial fast reaction of bromine with reovirus in turbulent flowing water. When quantitative electron microscopy shows that virus suspensions are essentially all single particles, the loss of infectivity follows first-order kinetics, the plaque titer falling at the rate of 3 log10 units/s at pH 7, 2 C, and at a 3-muM bromine concentration. Virus suspensions containing small aggregates (2 to 10/clump) exhibit a constantly decreasing disinfection rate with bromine. At a survival level of 10(-3) for single virions, the aggregated preparations have lost only 99% of their plaque titer and 10(-4) is reached only after 4 s of exposure. The disinfection rate does not appear to be a simple function of the size and frequency of aggregates in the virus suspension even when the aggregates contain no foreign material. Unpurified virus preparations (crude freeze-thaw lysates of infected cells) are shown, by zonal centrifugation, to contain 50% to over 90% of the infectivity in large, fast sedimenting aggregates. Such aggregates would strongly influence the bromine resistance of virus in polluted water.
Bromine↗
Inactivation by bromine of single poliovirus particles in water.
Quantitative electron microscopy shows that Freon-extracted poliovirus, velocity banded in a sucrose gradient, contains over 95% single particles. This well-dispersed virus reacts quite rapidly with bromine in turbulent flowing water, losing plaque titer at the rate of one log10 unit in 10s at pH 7, 2 C, and at a bromine concentration of 2.2 muM. At 10 and 20 C the rate of disinfection (log10 plaque-forming units per second) is faster, and at both temperatures it increases in approximately linear fashion with increasing bromine concentration. At 2 C such a linear relationship is not observed.
Bromine↗
Nature of the surviving plaque-forming unit of reovirus in water containing bromine.
The initial inactivation of reovirus in water containing 3 to 7 microns M bromine as HOBr was very rapid. Electron microscopy revealed extensive physical damage to the virions in as little as 1 min, but none were degraded beyond recognition. As treatment time continued, the reaction rate decreased toward a plateau of resistance, usually at about the 10-4 survival level; still no particles were lost. Progeny grown from these resistant plaque-forming units (PFU) were no more resistant to HOBr than the parent cultures. Small-number aggregation (adhering groups of two to ten virions counted by electron microscopy) had no detectable effect on the level of persistant PFU. Large aggregates seemed to be involved. Sonic treatment at 20 kHz after bromine exposure increased survival PFU titer 10- to 43-fold. Virus exposed to light centrifugation prior to bromine treatment did not show the plateau of resistance. Surviving PFU sedimented faster in a shallow sucrose gradient than single virions. Large aggregates were apparently too few to be counted by electron microscopy, but their penetration and inactivation must be achieved by any disinfectant chosen to rid water of reovirus.
Animals↗