Biomedical subjects

W Jakubowski

Publications and source records attributed to W Jakubowski.

At least 37 records · Page 2Linked to original sources

PubMed2000

[Magnetic resonance techniques used in the differentiation of adrenal tumors].

Noninvasive differentiation of adrenal masses by imaging studies as computed tomography and magnetic resonance imaging is an accepted diagnostic procedure in patients with extraadrenal neoplasm and discovered on imaging studies adrenal mass or in patients with incidentally discovered adrenal mass. Significant impact on possibilities of differentiation of adrenal masses with magnetic resonance imaging was due to introduction to adrenal imaging such techniques as chemical shift imaging and dynamic imaging with paramagnetic contrast agent. Differentiation of adrenal masses with magnetic resonance imaging involves following parameters: tumor diameter, signal intensity of adrenal mass on T2 weighted images, lipid contents in adrenal tumor evaluated with chemical shift imaging and washout of paramagnetic contrast agent from adrenal mass evaluated with dynamic examination. The best results, reaching 100% sensitivity and 100% specificity in differentiation adrenal adenomas from non-adenomas, can be achieved by combined analysis of all mentioned parameters. In regard to availability and costs computed tomography not magnetic resonance imaging is the examination of choice in visualization of adrenal glands and their pathology and in differentiation of adrenal masses. Adrenal tumors on non-enhanced images with density below 0 Hounsfield units can reliably be diagnosed as adenomas, whereas adrenal tumors with density above 20 Hounsfield units can reliably be diagnosed as non-adenomas. Tumors with density in 0-20 Hounsfield range are ambiguous in character, that in many cases can be determined in magnetic resonance imaging.

Adrenal Gland Neoplasms↗

PubMed1999

Sensitivity of antioxidant-deficient yeast Saccharomyces cerevisiae to peroxynitrite and nitric oxide.

Sensitivity of Saccharomyces cerevisiae strains deficient in superoxide dismutases and catalases and of decreased level of glutathione to peroxynitrite and a nitric oxide donor, S-nitrosoglutathione was compared. Moderate but significant differences observed point to increased sensitivity to both agents of yeast deficient in antioxidant defense, the superoxide dismutase-deficient strain showing the highest sensitivity, The sequence of sensitivity of various strains to peroxynitrite and nitric oxide was the same. The results are compatible with the view that cytotoxic effects of peroxynitrite involve formation of secondary reactive oxygen species.

Antioxidants↗

PubMed1999

Infectivity of Cryptosporidium parvum in healthy adults with pre-existing anti-C. parvum serum immunoglobulin G.

A 50% infectious dose (ID50) of 132 Cryptosporidium parvum oocysts was previously determined in serologically negative individuals (ELISA). In this study, 17 healthy adults with pre-existing anti-C. parvum serum IgG were challenged with 500-50,000 oocysts. Infection and diarrhea were associated with the higher challenge doses. The ID50 was 1,880 oocysts, > 20-fold higher than in seronegative volunteers. Fecal oocysts were detected in only seven (53.8%) of 13 individuals with clinical cryptosporidiosis, indicating that the host response may effectively decrease the number of oocysts produced. Subjects with the highest absorbances prior to challenge had little to no increase in IgG following challenge, whereas volunteers with lower reactivities showed significant postchallenge increases. This suggests that an upper limit of serum IgG was present in some subjects, while others were further stimulated by an additional exposure. These data indicate that prior exposure to C. parvum provides protection from infection and illness at low oocyst doses.

Adult↗

PubMed1998

Luminol luminescence induced by oxidants in antioxidant-deficient yeasts Saccharomyces cerevisiae.

Luminol chemiluminescence induced in the presence of yeast cells and yeast cell homogenates was significantly induced by exogenous oxidants (hydrogen peroxide and menadione). tert-Butyl hydroperoxide did not stimulate chemiluminescence by itself but augmented menadione-induced chemiluminescence. Comparison of yeast strains deficient in catalase, superoxide dismutase or glutathione showed that only glutathione-deficient strains showed elevated chemiluminescence in this system. These results support the idea that more reactive species than hydrogen peroxide and superoxide are critical in the induction of luminol chemiluminescence.

Acatalasia↗

PubMed1998

Susceptibility and serologic response of healthy adults to reinfection with Cryptosporidium parvum.

Healthy adults are susceptible to infection with small numbers of Cryptosporidium parvum oocysts, resulting in self-limited infection. We investigated if infection of humans with C. parvum is protective 1 year after primary exposure. At 1 year after a primary challenge with 30 to 10(6) oocysts, 19 healthy immunocompetent adults were rechallenged with 500 oocysts and monitored for the development of infection and/or illness. Oocyst excretion was quantitated by direct immunofluorescence with a C. parvum-specific monoclonal antibody, and anti-C. parvum antibodies in serum were detected by an enzyme-linked immunosorbent assay. Fewer subjects shed oocysts after the second exposure (3 of 19; 16%) than after the first exposure (12 of 19; 63%) (P < 0.005). Although the rates of diarrhea were comparable after each of the two exposures, the clinical severity as determined by the mean number of unformed stools passed was lower after reexposure (11.25 versus 8.62; P < 0.05). The number of anti-Cryptosporidium immunoglobulin G and A seroconversions increased after secondary exposure. However, the C. parvum serum antibody response did not correlate with the presence or absence of infection.

Adult↗

PubMed1997

Multiple adrenal masses: MRI tissue differentiation of pheochromocytoma and adenoma at 1.5 T.

We present the case of 38-year-old hypertensive patient with bilateral adrenal masses and with clinical and biochemical suspicion of pheochromocytoma. Magnetic resonance imaging at 1.5 T established correct diagnosis of coexisting adrenal pheochromocytoma and adenoma (nonhyperfunctioning). The case supports the usefulness of MRI for definitive evaluation of bilateral adrenal masses in patients with suspicion of pheochromocytoma.

Adenoma↗

PubMed1997

Estimation of oxidative stress in Saccharomyces cerevisae with fluorescent probes.

Oxidation of dichlorofluorescin and dihydrofluorescin and transport of their oxidation products were studied in Saccharomyces cerevisiae cells given diacetates of these compounds. It was found that addition of peroxidase significantly accelerates the formation of dichlorofluorescein and fluorescein, indicating that peroxidase activity may be a limiting factor in studies of cellular oxidation using these probes. A significant leakage of dichlorofluorescin and dihydrofluorescin, and of their oxidized forms from the yeast cells, was found, without any apparent lag period. This phenomenon complicates interpretation of data obtained with the fluorescent precursors used but, on the other hand, points to the possibility of using measurements of dichlorofluorescein or fluorescein in the extracellular medium for studies of cellular oxidation processes.

Biological Transport↗

PubMed1997

An in vitro method for detecting infectious Cryptosporidium oocysts with cell culture.

Current assay methods to detect Cryptosporidium oocysts in water are generally not able to evaluate viability or infectivity. A method was developed for low-level detection of infective oocysts by using HCT-8 cells in culture as hosts to C. parvum reproductive stages. The infective foci were detected by labeling intracellular developmental stages of the parasite in an indirect-antibody assay with a primary antibody specific for reproductive stages and a secondary fluorescein isothiocyanate-conjugated antibody. The complete assay was named the focus detection method (FDM). The infectious foci (indicating that at least one of the four sporozoites released from a viable oocyst had infected a cell) were enumerated by epifluorescence microscopy and confirmed under Nomarski differential interference contrast microscopy. Time series experiments demonstrated that the autoreinfective life cycle in host HCT-8 cells began after 12 h of incubation. Through dilution studies, levels as low as one infectious oocyst were detected. The cell culture FDM compared well to other viability assays. Vital stains and excystation demonstrated that oocyst populations less than 1% viable (by vital dyes) and having a low sporozoite yield following excystation could not infect host cells. Until now, the water industry has relied on an oocyst detection method (under an information collection regulation) that is unable to determine viability. The quantifiable results of the cell culture method described demonstrate two important applications: (i) an infectivity assay that may be used in conjunction with current U.S. Environmental Protection Agency-mandated detection methodologies, and (ii) a method to evaluate oocyst infectivity in survival and disinfection studies.

Animals↗

PubMed1996

Lack of evidence of oxidative damage in antioxidant-deficient strains of Saccharomyces cerevisiae.

The content of reactive carbonyls and of glutathione-protein mixed disulfides, two indices of oxidative stress, were compared in wild-type Saccharomyces cerevisiae and in strains deficient in superoxide dismutase and catalase, and of decreased glutathione level. Both indices were higher in stationary than in logarithmic cultures and were not increased in antioxidant-deficient strains. Oxidation of dichlorofluorescin, an estimate of peroxide production, measured in the presence of exogenous peroxidase, was higher in antioxidant-deficient strains. These results corroborate our previous results on compensatory antioxidant mechanisms in the mutant yeast strains.

Acatalasia↗

PubMed1995

The infectivity of Cryptosporidium parvum in healthy volunteers.

BACKGROUND: Small numbers of Cryptosporidium parvum oocysts can contaminate even treated drinking water, and ingestion of oocysts can cause diarrheal disease in normal as well as immunocompromised hosts. Since the number of organisms necessary to cause infection in humans is unknown, we performed a study to determine the infective dose of the parasite in healthy adults. METHODS: After providing informed consent, 29 healthy volunteers without evidence of previous C. parvum infection, as determined by the absence of anti-cryptosporidium-specific antibodies, were given a single dose of 30 to 1 million C. parvum oocysts obtained from a calf. They were then monitored for oocyst excretion and clinical illness for eight weeks. Household contacts were monitored for secondary spread. RESULTS: Of the 16 subjects who received an intended dose of 300 or more oocysts, 14 (88 percent) became infected. After a dose of 30 oocysts, one of five subjects (20 percent) became infected, whereas at a dose of 1000 or more oocysts, seven of seven became infected. The median infective dose, calculated by linear regression, was 132 oocysts. Of the 18 subjects who excreted oocysts after the challenge dose, 11 had enteric symptoms and 7 (39 percent) had clinical cryptosporidiosis, consisting of diarrhea plus at least one other enteric symptom. All recovered, and there were no secondary cases of diarrhea among household contacts. CONCLUSIONS: In healthy adults with no serologic evidence of past infection with C. parvum, a low dose of C. parvum oocysts is sufficient to cause infection.

Adult↗

PubMed1995

Identification of algae which interfere with the detection of Giardia cysts and Cryptosporidium oocysts and a method for alleviating this interference.

Fifty-four algal species were tested for cross-reaction in the American Society for Testing and Materials Giardia/Cryptosporidium indirect immunofluorescence assay, and 24 showed some degree of fluorescence. Two species, Navicula minima and Synechococcus elongatus, exhibited a bright apple green fluorescence. The addition of goat serum to the assay mixture blocked the fluorescence of most nontarget organisms tested and also decreased the background fluorescence. Goat serum did not interfere with the fluorescence of Giardia cysts or Cryptosporidium oocysts or the identification of cyst and oocyst internal structures.

Animals↗

PubMed1992

Differentiation of Giardia duodenalis from other Giardia spp. by using polymerase chain reaction and gene probes.

Giardia spp. are waterborne organisms that are the most commonly identified pathogenic intestinal protozoans in the United States. Current detection techniques for Giardia species in water include microscopy and immunofluorescence techniques. Species of the genus Giardia are classified on the basis of taxonomic criteria, such as cell morphology, and on host specificity. We have developed a polymerase chain reaction- and gene probe-based detection system specific for Giardia spp., which can discriminate between the relevant species of the G. duodenalis type pathogenic to humans and other Giardia species that are not human pathogens. This method can detect a single Giardia cyst and is therefore sensitive enough for environmental monitoring.

Animals↗

PubMed1991

Propidium iodide as an indicator of Giardia cyst viability.

The use of propidium iodide, whose uptake indicates cell death or damage, was investigated to assess the viability of heat-inactivated and chemically inactivated Giardia muris cysts. This was done by comparing propidium iodide staining with excystation. We first determined that propidium iodide could be used with an immunofluorescence detection procedure by showing that the percentages of Giardia lamblia cysts stained with this dye before and after subjecting them to a fluorescence detection method were similar. G. muris cysts were then exposed to heat (56 degrees C), 0.5 to 4 mg of chlorine per liter (pH 7.0, 5 degrees C), 0.1 to 10 mg of a quaternary ammonium compound per liter, or 2 mg of preformed and forming monochloramine per liter (pH 7.2, 18 to 20 degrees C). A good positive correlation between percent propidium iodide-stained cysts and lack of excystation was demonstrated for G. muris cysts exposed either to heat or to the quaternary ammonium compound. However, no significant correlation between absence of excystation and propidium iodide staining was found for cysts exposed to chlorine or monochloramines. These results demonstrate that the propidium iodide staining procedure is not satisfactory for determining the viability of G. muris cysts exposed to these two commonly used drinking water disinfectants.

Animals↗

PubMed1991

Detection of Giardia cysts by using the polymerase chain reaction and distinguishing live from dead cysts.

A method was developed for the detection of Giardia cysts by using the polymerase chain reaction (PCR) and the giardin gene as the target. DNA amplification by PCR, using giardin DNA as the target, resulted in detection of both live and dead cysts. When giardin mRNA was used as the target, the ability to amplify cDNA by PCR depended on the mode of killing. Cysts killed by freezing were not detected by PCR when giardin mRNA was the target. Cysts killed by heating or exposure to monochloramine, however, gave positive detection signals for both DNA and giardin mRNA targets. The amount of giardin mRNA and total RNA was significantly increased in live cysts following the induction of excystation. Cysts killed by freezing, heating, or exposure to monochloramine did not show a change in RNA content. The detection of the giardin gene by PCR permits a sensitive and specific diagnosis for Giardia spp. Discrimination between live and dead cysts can be made by measuring the amounts of RNA or PCR-amplified product from the giardin mRNA target before and after the induction of excystation.

Animals↗

PubMed1991

[Transesophageal and classical echocardiography in myocardial infarction and heart valve disease (comparison study)].

In 85 patients (22 with myocardial infarct and 63 with valvular heart disease) echocardiographical examination simultaneously by classical and transesophageal methods was done. The transesophageal method was better in assessing the aortic valve and similar to the classical method in reference to the mitral valve. Heart contractility assessment was better with the classical method. Transesophageal echocardiography is the method of choice in patients in whom classical echocardiography cannot be done (obesity, emphysema, chest deformation).

Adult↗

PubMed1990

Prevalence of Giardia spp. in beaver and muskrat populations in northeastern states and Minnesota: detection of intestinal trophozoites at necropsy provides greater sensitivity than detection of cysts in fecal samples.

Surveys of the prevalence of the intestinal protozoan Giardia spp. in animal populations have relied almost exclusively on the detection of cysts in fecal samples. We have determined the prevalence of Giardia spp. in beaver and muskrat populations in four northeastern states and Minnesota by using both the detection of trophozoites in mucosal scrapings from live-trapped animals at necropsy and the detection of cysts in fecal samples collected from kill-trapped animals. In muskrats the prevalence of Giardia infection was 36.6% by cyst detection in fecal samples (n = 790) from kill-trapped animals and 95.9% in live-trapped muskrats when the intestinal contents were analyzed for the presence of trophozoites (n = 219). Similarly, in beavers, Giardia infection was 9.2% by cyst detection in fecal samples (n = 662) from kill-trapped beavers and 13.7% in live-trapped animals examined for the presence of intestinal trophozoites (n = 302). The detection of trophozoites in mucosal scrapings from live-trapped animals consistently yielded a significantly higher prevalence for both muskrats and beavers than did the method based on detection of cysts in the fecal samples. The prevalence of Giardia infection in juvenile and adult live-trapped muskrats was similar (92.5 and 94.4%, respectively), but the prevalence in juvenile live-trapped beavers (23.2%) was significantly greater than that seen in the adult animals (12.6%). No difference in Giardia prevalence on the basis of sex was seen in either animal species. Regional variation, often statistically significant, was seen in the prevalence of Giardia in beavers in the northeastern states and Minnesota, but was not detected for muskrats.

Animals↗

PubMed1990

[Transesophageal echocardiography--our preliminary experience].

This study presents the initial experience of our department with transesophageal echocardiography. Transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) were performed simultaneously in 31 clinical patients (16 to 76 years old). 13 pts with aortic (9) and mitral (4) valve disease, 10 pts with ischemic heart disease (including 7 AMI), 3 pts with congestive cardiomyopathy, 2 pts with aortic aneurysm and 3 pts with other heart diseases. The investigations were performed with use of Aloka SSD 650 machine and 7.5 MHz transesophageal convex transducer. The patients were prepared for the examination in the typical way by local anesthesia, administration of sedatives and heart monitoring. The following projections were used: basic short- and long-axis view, four chamber view, and transgastric view. These investigation confirmed the usefulness TEE for evaluation of aortic and mitral valves, especially their morphology, atrial septum and atrial cavities. Contractility and other heart structures were difficult to be evaluated by TEE. It seems to be possible to estimate the proximal sections of the coronary arteries. Only few complications were found: supraventricular (2) and ventricular extrasystoles (8), transient supraventricular tachycardia (3), and bradycardia (3). Late complications were not found.

Adolescent↗

PubMed1990

Intrapericardial pheochromocytoma: a case report.

A patient with a pheochromocytoma located intrapericardially is described. 131I-labeled metaiodobenzylguanidine scintigraphy was helpful in locating the tumour. The operation and postoperative course were uneventful.

Adult↗