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Biomedical subjects

K Szabo

Publications and source records attributed to K Szabo.

At least 37 records · Page 2Linked to original sources
PubMed1998

In vivo detection of short- and long-term MDMA neurotoxicity--a positron emission tomography study in the living baboon brain.

The present study evaluated short- and long-term effects of MDMA (3,4-methylenedioxymethamphetamine) in the baboon brain using PET and [11C](+)McN 5652, a potent 5-HT transporter ligand, as well as [11C]RTI-55, a cocaine derivative which labels both 5-HT and dopamine transporters. Following baseline PET scans with [11C](+)McN5652, [11C](-)McN5652 (the inactive enantiomer of the active enantiomer [11C](+)McN5652) and [11C]RTI-55, a baboon was treated with MDMA (5 mg/kg, s.c., twice daily for four consecutive days). PET studies at 13, 19, and 40 days post-MDMA revealed decreases in mean radioactivity levels in all brain regions when using [11C](+)McN 5652, but not with [11C](-)McN5652 or [11C]RTI-55. Reductions in specific [11C](+)McN5652 binding (calculated as the difference in radioactivity concentrations between (+) and (-)[11C]McN5652) ranged from 44% in the pons to 89% in the occipital cortex. PET studies at 9 and 13 months showed regional differences in the apparent recovery of 5-HT transporters, with increases in some brain regions (e.g., hypothalamus) and persistent decreases in others (e.g., neocortex). Data obtained from PET studies correlated well with regional 5-HT axonal marker concentrations in the CNS measured after sacrifice of the animal. The results of these studies indicate that PET imaging of the living nonhuman primate brain with [11C](+)McN5652 can detect changes in regional 5-HT transporter density secondary to MDMA-induced neurotoxicity. Using PET, it should also be feasible to use [11C](+)McN5652 to determine whether human MDMA users are also susceptible to MDMA's neurotoxic effects.

Animals↗
PubMed1998

Systematic gain-of-function genetics in Drosophila.

A modular misexpression system was used to carry out systematic gain-of-function genetic screens in Drosophila. The system is based on inducible expression of genes tagged by insertion of a P-element vector carrying a GAL4-regulated promoter oriented to transcribe flanking genomic sequences. To identify genes involved in eye and wing development, the 2300 independent lines were screened for dominant phenotypes. Among many novel genes, the screen identified known genes, including hedgehog and decapentaplegic, implicated in these processes. A genetic interaction screen for suppressors of a cell migration defect in a hypomorphic slow border cells mutant identified known genes with likely roles in tyrosine kinase signaling and control of actin cytoskeleton, among many novel genes. These studies demonstrate the ability of the modular misexpression system to identify developmentally important genes and suggest that it will be generally useful for genetic interaction screens.

Animals↗
PubMed1996

Evaluation of verification assays in EIA specimens presumptively positive for Chlamydia trachomatis.

Verification of specimens positive for Chlamydia trachomatis by enzyme immunoassay (EIA) has been recommended when testing low prevalence populations. This study compared direct fluorescent antibody (DFA) and blocking antibody (BLA) verification assays in specimens presumptively positive for C. trachomatis by the Syva Microtrak II EIA. Of 1785 specimens originally tested by EIA, 96 were presumptively positive for C. trachomatis. Verification assays were concordant in 86 specimens (69 positive, 17 negative); nine of the remaining samples gave positive results in a second EIA and one was unresolved. Both verification assays gave some false-negative results. When initial EIA absorbance values were correlated with verified results, all EIA false positive results had absorbances in the low range (less than a three-fold increase over assay cut-off values). Verification of EIA results by both DFA and BLA was effective in detecting false positive results, but confining verification to low-value positive specimens could be considered for cost effective C. trachomatis testing.

Antibodies, Bacterial↗
PubMed1993

Human infectious corneal ulcer caused by Pythium insidiosum.

Pythium insidiosum is a fungus-like organism known to infect a variety of animals. In humans, the few known cases involving Pythium have included arterial infections and cellulitis. We present what we believe to be the first case of P. insidiosum recovered from a human corneal ulcer. The organism is difficult to isolate, causing delays in diagnosis. It is also resistant to the usual antifungal medications, making surgical excision the treatment of choice.

Adult↗
PubMed1992

Increase of the chlorophyll fluorescence ratio F690/F735 during the autumnal chlorophyll breakdown.

The chlorophyll content and the fluorescence induction kinetics at two wavelengths (690 nm and 735 nm) have been measured in leaves of nine common broadleaf tree species during the autumnal chlorophyll breakdown. The ratio of the chlorophyll fluorescence maxima F690/F735 was determined at fluorescence maximum (fm) and at steady-state conditions (fs) by the laser-induced fluorescence emission using the two-wavelength fluorometer. The ratio F690/F735 increases with the leaf discolouring during the autumnal chlorophyll breakdown. The relationship between the chlorophyll content and the ratio F690/F735 can be expressed by a power function (curvilinear relationship) which is valid for all the species examined. In most cases the ratio F690/F735 measured in the upper leaf side is lower than that in the lower leaf side, but the trend is the same along the decreasing chlorophyll content. The ratio F690/F735 is always higher at maximum fluorescence than at steady-state fluorescence in the upper as well as lower leaf side and these values are well fitted in a linear correlation. This study confirms the usefulness of the ratio F690/F735 as a suitable non-destructive indicator of the in-vivo chlorophyll content, especially at medium and low chlorophyll content.

Chlorophyll↗
PubMed1992

Evaluation of three immunoassays for detection of Chlamydia trachomatis in urine specimens from asymptomatic males.

The performances of three commercially available immunoassays (Chlamydiazyme/Antibody Blocking Assay [Abbott Diagnostics, Abbott Park, Ill.], IDEIA [Analytab Products, Plainview, N.Y.], and Microtrak EIA [Syva Co. Palo Alto, Calif.]) were evaluated for the detection of Chlamydia trachomatis in urine specimens from asymptomatic males. Assay results were compared with direct specimen immunofluorescence (DFA) analysis of urine sediment (Syva Microtrak; Syva Co.), which was chosen as the study confirmation assay. An overall Chlamydia prevalence of 7% (24 of 340) was found in our study population, with peak incidences occurring in the adolescent (8 of 93 specimens) and young adult (11 of 146 specimens) age groups. Sensitivity and specificity data among the Chlamydiazyme, IDEIA, and Microtrak enzyme immunoassays (EIAs) were determined to be 79.1 and 99%, 91.7 and 98%, and 95.8 and 99%, respectively. The Microtrak EIA and IDEIA products demonstrated sensitivities and specificities equal to or greater than those claimed for urine specimens. The diagnostic accuracies of these assays on asymptomatic subjects, along with the ease of this collection method, suggest a role for these products as screening tools. The sensitivity of the Chlamydiazyme assay was lower than that claimed previously in symptomatic patients, with 5 of 24 positive specimens demonstrating false-negative results. In those cases, centrifugation of the original immunoassay aliquot material and then DFA examination confirmed specimen positivity. Urine immunoassay screening in combination with DFA confirmation (which was chosen because it has antibody epitopic specificity different from that of the primary assay) provides a high degree of diagnostic precision. The use of noninvasive collection methods could result in greater testing compliance among asymptomatic males and, subsequently, could reduce the incidences of both symptomatic and silent chlamydial infections.

Adolescent↗
PubMed1992

[The Budapest agglomeration, 1980-1990].

"The study analyses the development of Budapest and [the] 6 towns and 37 communes forming its conurbation between 1980 and 1990." Consideration is given to the city's population dynamics; housing conditions, including availability of utilities, transportation, telecommunications, and retail stores; health conditions of the population; and educational opportunities for residents. (SUMMARY IN ENG AND RUS)

Communication↗
PubMed1988

Changing patterns of genital herpes simplex virus infections.

Herpes simplex virus type 2 is considered by many venereologists as the predominant serotype among those patients suffering from genital herpes. However, identification of genital isolates obtained from 16 through 20, and 31 through 40 year old individuals among our female patient population shows a predominance of HSV-1 infections. These data suggest that the "above the waist"-"below the waist" epidemiologic patterns commonly ascribed to reflect a prevalence of HSV-1 and HSV-2 infections respectively, may no longer be appropriate in certain patient populations.

Adolescent↗
PubMed1988

Sensitivity of rhabdomyosarcoma and guinea pig embryo cell cultures to field isolates of difficult-to-cultivate group A coxsackieviruses.

Forty-two difficult-to-cultivate group A coxsackieviruses (i.e., group A types other than A7, A9, and A16), collected primarily from throat swab specimens of patients suffering from fever, pharyngitis, lymphadenopathy, and cough during the 1986 enterovirus season, were isolated in less than 24-h-old suckling mice. Thirty-six moribund mice were sacrificed and autopsied, and then their brains and back musculature were inoculated into rhabdomyosarcoma (RD), guinea pig embryo (GPE), rhesus monkey kidney (RhMk) and human carcinoma of the larynx (HEp-2) cell cultures. Twelve of the 36 suckling mice isolates were adapted to grow in RD and GPE cells after two passes and have been identified in RD cells by type-specific antisera as group A coxsackievirus types A2, A4, and A8. Three passes in RhMk or HEp-2 cell cultures were insufficient to affect a discernible cytopathic effect. Coxsackievirus types A1, A19, and A22, unable to grow in any of the four cell cultures tested, were identified by virus neutralization in suckling mice. These data denote the efficacy of suckling mice for the isolation of difficult-to-cultivate group A coxsackieviruses.

Animals↗
PubMed1987

Evaluation of three immunofluorescence assays for culture confirmation and typing of herpes simplex virus.

Three pairs of monoclonal antibodies, supplied in kits by Electro-Nucleonics, Inc. (ENI), The Syva Co., and Kallestad Laboratories, Inc. (KL), were evaluated for the laboratory confirmation and typing of herpes simplex virus (HSV). Of 108 coded HSV slide preparation, run in parallel with each monoclonal-antibody set, 103 were equivalent by the immunofluorescence assays. Among the five discordant isolates, three (2.8%) did not type with the KL monoclonal antibodies and two (1.9%) false-positive results occurred with the Syva typing system. All of the HSV clinical isolates tested were correctly typed with the ENI indirect immunofluorescence antigen detection system. Typing confirmation of the five discordant HSV isolates was performed by differential sensitivity to 5-bromo-2'-deoxyuridine and endonuclease cleavage analysis of the viral DNA. Use of the Syva and KL direct immunofluorescence antigen detection systems for the identification of HSV isolates is less time-consuming than use of the ENI indirect antigen detection system; however, sensitivity and specificity may be lost.

Antibodies, Monoclonal↗
PubMed1985

Overwhelming post-splenectomy infection with Plesiomonas shigelloides in a patient cured of Hodgkin's disease. A case report.

The immune deficiencies of Hodgkin's disease persist to some degree even after the patients are clinically cured; these may be amplified by loss of splenic immunologic functions after staging laparotomy and splenectomy. The authors submit a case report wherein a bacterium of relatively low virulence, Plesiomonas shigelloides, was associated with a rapidly fulminant septicemia, disseminated intravascular coagulation, Waterhouse-Friderichsen syndrome, and death in a splenectomized patient free of Hodgkin's disease for approximately five years. This emphasizes the need for prolonged observation, rapid diagnosis, and aggressive intervention in immunocompromised patients, especially those supposedly cured of previous hematologic malignancy.

Adult↗
PubMed1977

Ocular immunopathology in murine lupus.

Immunoglobulin deposits and DNA were identified by use of immunofluorescence microscopy within the ciliary process and choroid of a majority of (NZB X W)F1 mice with murine lupus. The number of animals with such deposits increased from 57% at 36 weeks of age to 90% at one year of age. Ultrastructural examination showed electron-dense deposits between the basement laminae of the endothelium and pigmented epithelium of the ciliary process, accompanied by alterations in the epithelial basement membranes. Similar electron-dense deposits were also identified in the vicinity of the lamina choroidocapillaris. The titer of antibody to DNA did not correlate with the presence of ocular deposits, suggesting that time is an important factor in the development of ocular immunopathology in these animals.

Age Factors↗
PubMed1976

Relationship of subepidermal immune complex to renal deposits in the (NZB X W)F1 mouse.

In an attempt to correlate the presence of subepidermal and renal glomerular deposits in murine lupus, skin and kidney tissue from 67 (NZB X W)F1 mice was examined by direct immunofluorescence and the results tabulated. Between 36 and 43 weeks of age, deposits in both locations were detected in only 50.5% of the mice, and between 44 and 52 weeks, in only 79.0%. The titer of antibody to DNA did not correlate with the presence of subepidermal deposits even though DNA was demonstrated at the epidermal-dermal interface. It is concluded that the absence of immunoglobulin in the subepidermis does not preclude the presence of renal deposits, and it is hazardous to attempt to predict underlying glomerular deposition by performing immunofluorescence examination of skin in murine lupus.

Age Factors↗
PubMedDate not supplied

Stereologic evaluation of the vasculature in a MX1 xenotransplanted tumour model after combinations of treatment with ifosfamide, hyperthermia and irradiation.

The vascularization of tumours is a critical parameter of their growing and metastatic behaviour. However, little is known about the morphologic reactions of the microvasculature, especially the capillary bed of tumours and the adjacent tissue. In this study, the vessels in MX1 xenotransplants in athymic nu/nu nude mice were quantified and the angioarchitecture was visualized with the aim of presenting stereologic parameters of vessels based on a morphometric analysis of post mortem tissue blocks which were processed by standard histological procedures. In order to study changes of the microvasculature of MX1 tumours, the xenotransplanted nude mice were treated by different therapeutic regimens. Standardized hyperthermia, ifosfamide and irradiation therapies were applied. Special interest was focused on early changes of capillaries and of the pre- as well as post-terminal vascular bed. The stereologic evaluation of capillaries and larger vessels immediately after the therapy with ifosfamide and hyperthermia shows an increase of the mean capillary sizes. Furthermore, tumour samples after the 5th day of irradiation (5 x 2 Gy) and combinations of irradiation and chemotherapy treatment have been investigated. After 5 days of irradiation, a significant decrease of the vascular density was found. The results presented here clearly show that the timing and the mode of therapy influence the capillary morphology and periterminal vasculature of xenotransplanted MX1 tumours.

Animals↗