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Biomedical subjects

M Novak

Publications and source records attributed to M Novak.

At least 55 records · Page 3Linked to original sources
PubMed1997

Alteration in brain metabolites of jirds infected with alveolar Echinococcus.

The Meriones unguiculatus-Echinococcus multilocularis host-parasite system was used to evaluate changes in metabolite levels in the brain of the infected host. Nuclear magnetic resonance analysis of perchloric acid extracts of the entire brain of jirds revealed that infection caused a change in the concentration of several metabolites, especially those that serve as amino acidergic neurotransmitters in this organ. The concentrations of the neuroexcitatory compounds glutamate and aspartate and the neuroinhibitory compounds glycine and taurine were significantly reduced. Those of 2 other amino acids, glutamine and alanine, were also decreased. In addition, concentrations of glycerophosphocholine and phosphocholine were also lower, whereas those of phosphocreatine and N-acetylaspartate were elevated.

Amino Acids↗
PubMed1996

Calcium/calmodulin-dependent protein kinase II phosphorylates tau at Ser-262 but only partially inhibits its binding to microtubules.

PHF-tau, which is phosphorylated at 10 Ser/Thr-Pro and 11 non-Ser/Thr-Pro sites, is unable to promote microtubule assembly. Phosphorylation of the non-Ser/Thr-Pro site, Ser-262, is reported to be primarily responsible for this. The identities of kinase(s) responsible for Ser-262 phosphorylation are still to be clarified. In this study we have used the monoclonal antibody 12E8, which recognizes P-Ser-262 and P-Ser-356 on tau, to survey different kinases for their abilities to phosphorylate Ser-262 on human tau 3L (tau410). In decreasing order of effectiveness we found that Ser-262 and Ser-356 phosphorylation can be catalyzed by CaM kinase II >> C-kinase >> GSK-3 approximately = A-kinase >> CK-1. CaM kinase II and C-kinase were shown to phosphorylate both Ser-262 and Ser-356. The binding of tau to taxol-stabilized microtubules was decreased by 35 and 42% after phosphorylation by CaM kinase II and C-kinase, respectively. Of the fraction of tau that bound to microtubules, about 50% was phosphorylated at Ser-262 and Ser-356. These results suggest that Ser-262 and Ser-356 are very good substrates for CaM kinase II but their phosphorylations are not sufficient to achieve maximal inhibition of tau binding to microtubules.

Binding Sites↗
PubMed1996

Manipulating systemic and mucosal immune responses with skin-deliverable adjuvants.

Most medically important bacterial and viral pathogens gain entry into the body either via the skin or a mucosal surface. Vaccination provides a viable and cost-effective strategy for the prevention of such diseases and it has always been a principal aim with vaccinologists, to be able to promote simultaneously, protective immune responses both systemically and at mucosal surfaces. The paradigm that mucosal immunity is best stimulated by exposure to antigen via a mucosal route simply because inductive sites such as Peyer's patches and bronchial associated lymphoid tissues are located in the mucosal epithelium, has promoted a plethora of immunizing strategies aimed at delivering both antigen and adjuvant to mucosal surfaces. We have developed a novel adjuvant system capable of intradermal delivery of antigens complexed in an ISCOSOME delivery vehicle. This adjuvant, referred to as a skin and mucosal adjuvant or SAMA4, was efficacious in eliciting both systemic and mucosal IgG and IgA antibodies in sheep, pigs and mice. SAMA4 does not induce granulomatous lesions at the site of vaccine delivery and can be used to deliver adjuvanted antigens by other routes including intranasal, oral and intravaginal. Using ovalbumin as a test antigen, intradermally delivered ovalbumin-SAMA4 complexes was found to be very effective in promoting a cytotoxic T cell response. Attempts to dissect the mode of action of SAMA4 by flow cytometric analysis of lymphocyte populations from the spleen, lung, liver and thymus revealed an effect of route of vaccine delivery upon the composition of specific lymphocyte subsets in these various organ compartments. From this, it can be inferred that SAMA4 induced a route-dependent re-mobilization and alteration in lymphocyte trafficking patterns. Other mucosal adjuvants such as cholera toxin B and microspheres, when injected intradermally, tended to promote primarily, an IgG and not an IgA response against hte carrier antigen.

Animals↗
PubMed1996

Long-term productive human cytomegalovirus infection of a human neuroblastoma cell line.

Human neuroblastoma cell line UKF-NB-4 persistently infected with human cytomegalovirus (HCMV) strain AD169 was established to study the effects of long-term HCMV infection on virus production and phenotypic characteristics of tumour cells. The cells designated UKF-NB-4AD169 were subcultured (80 subcultures) over a period of more than 2 years after initiation of infection. UKF-NB-4AD169 cells continued to produce infectious virus in successive passages, with a titre ranging from 9 x 10(3) to 1 x 10(5) and from 2 x 10(1) to 2 x 10(2) plaque-forming units per 10(6) cells and 1 ml culture medium, respectively; 10-20% of the cells produced HCMV-specific antigens, while 6-13% produced infectious virus progeny. The number of HCMV-specific DNA copies ranged from 9 x 10(4) to 9 x 10(6) per 10(6) cells. Transmission electron microscopy confirmed the productive nature of HCMV infection. UKF-NB-4AD169 cultures proliferated, with population doubling time ranging from 24.5 to 26.6 hr (19.5 to 20.3 hr for UKF-NB-4) and cell viability from 79% to 85% (91-96% for UKF-NB-4). Significantly lower amounts of tyrosine hydroxylase and decreased activity for dopamine-beta-hydroxylase than in uninfected cells were observed in UKF-NB-4AD169 cells. However, the expression of N-myc oncoprotein was significantly increased in persistently infected cultures. Our results show that long-term productive HCMV infection of UKF-NB-4 cell line is associated with the modulation of phenotypic properties, which may be related to the biological behaviour of neuroblastoma cells.

Cell Differentiation↗
PubMed1996

A NMR study of parasitized Tenebrio molitor and Hymenolepis diminuta cysticercoids.

In vivo NMR spectra of uninfected and Hymenolepis diminuta-infected Tenebrio molitor fed D-(1-13C)glucose showed that infected beetles of both sexes had a significantly higher ratio for (glycogen C1/lipid (CH2)n) than the corresponding controls. Quantitative metabolic profiles and the per cent 13C-label in metabolites, based on NMR of perchloric acid extracts, are presented for control and infected beetles fed D-(1-13C)glucose and for H. diminuta cysticercoids. Female beetles, both control and infected, contained more glycogen than their male counterparts and infected beetles of both sexes possessed less glycerophos-phocholine, but more glycogen and a higher percentage label in glucose and trehalose than their respective controls. Label was also incorporated into glycogen, succinate, acetate, alanine and lactate. Extracts of cysticercoids from beetles fed D-(1-13C)glucose contained the following labelled compounds, in order of decreasing per cent 13C label: glucose, trehalose, alanine, succinate, lactate, glycogen and acetate. In vitro cultivation experiments, employing D-(1-13C)glucose, revealed that trehalose found in cysticercoids was of parasite, and not beetle, origin.

Amino Acids↗
PubMed1996

The impact of cognitively impaired patients and shift on nursing assistant stress.

This study compared the stress experienced by nursing assistants (NAs) under four work conditions: high or low proportion of cognitively impaired patients and day or other shift. Five standard measures of caregiver stress served as the dependent variables in this study; burden, reaction to patient behaviors, workload, and two measures of burnout. A 2x2 multivariate analysis of variance found an interaction effect of type and shift on the stress measures. Univariate tests found that Burden and Depersonalization accounted for this effect. A further multivariate analysis of simple main effects found significant differences for each independent variable within each level of the other independent variable. Univariate analysis found that NAs who care for cognitively impaired patients on the day shift show significantly higher scores on specific stress measures. The article concludes with a discussion of how institutions can respond to the stresses faced by NAs who care for cognitively impaired patients.

Adult↗
PubMed1996

[Clinical use of polymerase chain reaction in diagnosis and monitoring of malignant diseases].

The polymerase chain reaction (PCR) has revolutionized the diagnosis of leukemias, lymphomas and solid tumors over the past 10 years. This molecular method can amplify tumorspecific DNA or RNA markers by a factor of up to 1 x 10(6). Clinical applications include: (1) improvement of histologic diagnosis through the detection of clonality and definition of molecular markers specifically associated with certain disease; (2) prognostic assessment at diagnosis, with impact on initial therapeutic decisions; (3) monitoring of minimal residual disease and early detection of impending relapse after chemotherapy or bone marrow transplantation; (4) detection of residual tumor cells in bone marrow and peripheral blood stem cell harvests; (5) diagnosis of hereditary tumor syndromes. A number of these PCR assays is already incorporated in routine laboratory diagnostic procedures, especially in acute and chronic leukemias. The final goal of the clinical application of PCR is the development of risk adapted therapeutic concepts for neoplastic disease.

Biomarkers, Tumor↗
PubMed1995

Quick purification of recombinant human truncated tau proteins for immunoanalysis.

A simple and rapid purification method is described which exploits the heat stability of human tau (tau) protein to prepare truncated forms of this protein derived from bacteria. Bacterial cells expressing tau fragments were pelleted, resuspended in phosphate buffered saline and boiled for 5 min. After centrifugation the supernatant containing thermostable tau was filtered (0.45 microns) and used for immunoanalysis with monoclonal antibodies. The purified tau fragments exhibited identical antigenic properties as fragments isolated by a conventional procedure, based on ion exchange chromatography on phosphocellulose. In contrast to the conventional approach, our method is less complicated, cheaper and significantly reduces the time required for isolation of the recombinant tau fragments.

Antibodies, Monoclonal↗
PubMed1995

Alzheimer paired helical filaments, untreated and pronase digested, studied by vertical platinum-carbon replication and high resolution transmission electron microscopy.

Untreated paired helical filaments (PHF) and pronase treated PHF filaments have been stereoscopically imaged with a freeze-drying vertical platinum-carbon replication preparation method for TEM. The untreated PHF have an average wide region, W = 22.8 +/- 2.4 nm, a narrow region width, T = 10.6 +/- 1.7 nm, and a helical turn period, L = 78.6 +/- 13.4. The widths of the pronase treated PHF were significantly reduced and had average measurements of W = 14.8 +/- 1.2 nm, T = 5.7 +/- 1.0 nm, with the helical period unchanged, L = 75.4 +/- 17 nm. The surfaces of the untreated PHF contained approximately 1.0 and approximately 0.4 nm strands, the size of normal and denatured tau monomer. The pronase treated PHF contained approximately 1.0 and approximately 0.4 nm strands as well as approximately 2.0 nm strands. The stereoscopic images of the untreated and the pronase digested PHF do not support a double helical morphology for the PHF. The PHF appear to be long helical ribbons. The approximately 1.0 and approximately 2 nm substructure has been organized both parallel and orthogonal to the PHF-core axis for distances less than 80 nm. The most frequent structural appearance is of a disorganized PHF core. The surfaces of the untreated PHF also have a similar disorganized appearance.

Alzheimer Disease↗
PubMed1995

Phosphate metabolites of Tenebrio molitor (Coleoptera: tenebrionidae) infected with metacestodes of Hymenolepis diminuta.

In vivo phosphorus-31 nuclear magnetic resonance (31P NMR) spectra and those of extracts of Tenebrio molitor L. infected with metacestodes of Hymenolepis diminuta R. showed modifications in the amounts of phosphorous-containing metabolites when compared with those of uninfected beetles. Infected females were more affected than infected males, having significantly more glucose-6-phosphate (Glu-6-P), glycerol-3-phosphate (Gly-3-P), and phosphorylethanolamine (PE), but less inorganic orthophosphate (Pi), glycerophosphorylethanolamine (GPE), gylcerolphosphorylcholine (GPC), phosphoarginine (PAr), and adenosine diphosphate (ADP). Infected males had more Glu-6-P and PE, but less Pi, GPE, and GPC. These changes directly reflected the phosphorylation potential of infected hosts, which increased approximately 100% and 50% in infected females and males, respectively.

Animals↗
PubMed1995

The role of plasma exchange in the treatment of severe forms of hemolytic-uremic syndrome in childhood.

Therapeutic plasma exchange (PE) or plasma-pheresis has been used in recent years in the treatment of severe hemolytic uremic syndrome (HUS) in children. We analyzed the benefit of PE and peritoneal dialysis (PD) in 9 children, 6 boys and 3 girls, aged 1-10 years, from 1983-1993. All children came from different geographical regions, and all had the sporadic form of the illness. Three patients had the gastrointestinal form, 5 had respiratory prodromes while 1 child developed HUS during the course of varicella. Seven children were hypertensive, but only in 3 was hypertension persistent. The child with varicella had a transient complement decrease. Five children were treated with PE. In 4 children, fresh frozen plasma (FFP) was used as replacement fluid, and human albumin was used in 1 child. Four children were treated with PD and infusions of FFP. Rapid recovery of renal function was observed in 5 patients whereas in 2 oliguric children the recovery of renal function ensued within 1 and 2 months, respectively. Two children developed terminal renal failure (TRF) (in 1 child the treatment was very delayed, and in other child HUS developed following varicella). Only 1 boy had relapses of the disease followed by impairment of renal function from which he gradually recovered. During the 3-10 year follow-up period, only the child with relapses was hypertensive while the others had normal clinical and laboratory parameters. We suggest that PE plays an important role in the early treatment of severe forms of HUS in children.

Case-Control Studies↗
PubMed1995

Ig-secreting and interferon-gamma-producing cells in mice mucosally immunized with influenza virus.

1. Oral immunization of mice with influenza virus type A/Udorn, induced antigen-specific IgA antibodies in external secretions (e.g., saliva and fecal extract). 2. Increased numbers of antigen-specific IgA spot-forming cells (SFC) were seen in mononuclear cells isolated from IgA-effector tissues (e.g., SG) of mice orally-immunized with influenza virus. 3. Following oral or systemic immunization of mice, IFN gamma-secreting cells (Th1 type) displayed a characteristic pattern of distribution which was related to the route of immunization.

Administration, Oral↗
PubMed1995

[Treatment of septic shock in pediatrics].

A significant improvement has been noticed over the last 20 years in children in whom shock syndrome has developed. This has been attained through the application of technological advances in respiratory, cardiovascular, renal, nutritional support and improved antibacterial and antifungal therapy, but mostly through a better understanding of the physiology of shock. Newer concepts of the pathophysiology of sepsis and septic shock are presented, with clinical definitions referring to the pediatric patient. Innovative therapeutic modalities designed to modulate the systemic inflammatory response triggered by bacterial infection are discussed.

Child↗
PubMed1995

A case of fatal sepsis in a child due to highly resistant Streptococcus pneumoniae.

Infection with Streptococcus pneumoniae continues to be a significant cause of morbidity and mortality. Most of the pneumococci remain exquisitely sensitive to penicillin. However, S. pneumoniae with a reduced susceptibility to penicillin has been reported. To our knowledge, we present the first case in Croatia of fatal sepsis in a child due to Streptococcus pneumoniae that was highly resistant to penicillin.

Drug Resistance, Microbial↗
PubMed1995

[Paracetamol poisoning--case report].

A case of paracetamol poisoning in 17-month-old girl is presented. Clinical features and therapeutic procedures are described. Differences in paracetamol metabolism between children and adults are compared. Differences in the incidence of paracetamol poisoning between Croatia and USA are surveyed. The role of a physician in the education of parents and medical stuff on paracetamol toxicity is emphasized.

Acetaminophen↗
PubMed1994

Aphidicolin induces myogenic differentiation in the human rhabdomyosarcoma cell line KFR.

The effects of aphidicolin, a specific inhibitor of DNA polymerase alpha, on cell growth, DNA synthesis and myogenic differentiation in the human alveolar rhabdomyosarcoma cell line KFR were studied. The treatment with aphidicolin at 5 x 10(-6) M concentration, which completely inhibited DNA synthesis and cell growth, induced morphological differentiation of small mononuclear cells to elongated, multinucleated (myotube-like) structures. The morphological differentiation was accompanied by the expression of skeletal muscle myosin; about 30% myosin-positive cells were observed after 14 days of treatment, compared to 2.3% in untreated cultures. The results showed that aphidicolin induces differentiation of human rhabdomyosarcoma cells and that multinucleated myotube-like elements may develop simply by cell fusion without cell division and DNA synthesis.

Aphidicolin↗