Zlatko Kniewald

Zlatko Kniewald
University of Zagreb · Faculty of Food Technology and Biotechnology (PBF)

professor emeritus, PhD, MSc, dipl eng biotechnology

About

70
Publications
11,557
Reads
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1,207
Citations
Introduction
Zlatko Kniewald is professor emeritus previously working at the Faculty of Food Technology and Biotechnology (PBF), University of Zagreb. Zlatko does research in Bioengineering, Clinical Pharmacology and Toxicology. His last publication is 'Role of Croatia in the field of biotechnology'.
Additional affiliations
April 1987 - September 2008
University of Zagreb
Position
  • Professor Emeritus
Description
  • Head of the Laboratory for Cell Culture Technology, Application and Biotransformation
January 1981 - December 2008
Faculty of Food Technology nad Biotechnology
Position
  • Prof. emeritus U. of Zagreb, Professor of biochemical engineering, PhD Chemistry of Steroid Hormones, MSc Physical Chemistry, Dipl. eng. Biotechnology.
Description
  • From 1968 - 1975 Laboratory for Experimental Medicine, University of Zagreb
October 1968 - June 1970
University of Milan
Position
  • Ford Foundation Fellow
Description
  • Research on endocrine mechanisms within hypothalamo-pituitary-gonadal axis and study conversion of testosterone at DHT on the pituitary level
Education
October 1968 - June 1970
University of Milan
Field of study
  • Neuroendocrinology and neuroregulation
September 1968 - May 1970
University of Zagreb
Field of study
  • Biochemistry
September 1961 - April 1966
University of Zagreb
Field of study
  • Physical Chemistry

Publications

Publications (70)
Chapter
Full-text available
Za Godišnjak HATZ 2018 INOVACIJA, a na temu "Inovacije i patenti članova Akademije tehničkih znanosti Hrvatske", prilog u nastavku pri uređivanju negdje je zagubljen. Sada predlažem Uredništvu HATZ da ga sada uključi u Godišnjak 2020. zajedno sa znanstvenim radom našeg tima koji je objavljen 2006. godine i rezultat je navede-noga istraživanja. Baza...
Chapter
Full-text available
Razvoj biotehnologije u Hrvatskoj započeo je 1956. godine, osnivanjem jednog od prvih studija Biotehnologije u Europi na Sveučilištu u Zagrebu, Hrvatska, Europa na tadašnjem Tehnološkom fakultetu, a danas je to Prehrambeno-biotehnološki fakultet (PBF) Sveučilišta u Zagrebu. Osnivanje fakulteta ostvareno je u suradnji s tvrtkom PLIVA koja je tada po...
Article
Full-text available
There is considerable concern about the substances present in the environment and their potential to interfere with the endocrine system of vertebrates. Among these, the so-called endocrine-disrupting compounds, which can modulate or disrupt developmental and reproductive processes, substances with estrogenic activity have attracted most attention....
Article
Full-text available
The effects of synthetic estrogens 17α-ethynylestradiol (EE2) and diethylstilbestrol (DES) were compared on cell proliferation and morphology in Channel Catfish Ovary (CCO) and Chinese Hamster Ovary (CHO-K1) cells. EE2 exposure (0.1 and 0.5 μg/mL) induced stimulatory effect on CCO and CHO-K1 cell proliferation, while higher concentrations (1-10 μg/...
Article
Full-text available
In this study the effects of ammonium and lactate on a culture of channel catfish ovary (CCO) cells were examined. We also made investigation on the influence of glutamine, since our previous research revealed that this amino acid stimulated CCO cell growth more than glucose in a concentration-dependent manner. The effect of ammonium in cell cultur...
Article
Lindane, a toxic insecticide from the persistent organic pollutants (POP's) group, may act as an endocrine disrupter affecting crucial tissues of reproductive system. In this study a Chinese Hamster Ovary cell line (CHO-K1) was applied to assess the potential of lindane cytotoxicity at the cellular level. The methods of Trypan blue exclusion, MTT a...
Article
Full-text available
Growth factors from neural tissues have been described as potent mitogens for a wide variety of mesoderm- and ectoderm-derived cells in vitro. We used porcine brain extract for in vitro testing of proliferation properties on primary ovarian cells, uterine cells, and cardiomyocytes in culture as well as for BHK-21 [C-13] cell line. The addition of t...
Article
The aim of this study was to determine the toxic effect of atrazine at the ovarian cellular level. Chinese Hamster Ovary (CHO-K1) cell line was used to evaluate the degree of in vitro atrazine cytotoxicity and the morphological changes were followed during the cell death. Application of four bioassays confirmed that atrazine decreases ovarian cell...
Article
Full-text available
The growth characteristics and influence of glucose and glutamine on the growth and maintenance of channel catfish ovary (CCO) cells were investigated. Besides glutamine, amino acids threonine, arginine, methionine and serine were found to be essential for CCO cell growth. In the glucose-free medium, glutamine is utilized as energy source and no ce...
Article
Atrazine is shown to be responsible for serious failures involved in reproductive processes. The aim of the study is to evaluate the changes in tissues involved in production of peptide and steroid hormones regulated by feedback mechanisms in the rats. Male rats were treated i.p. with 120 mg of atrazine/kg b.w. during 60 days twice a week, while fe...
Article
The effects of lindane (γ-1,2,3,4,5,6-hexachlorocyclohexane) on male reproductive parameters were studied in rats. The testicular sperm number, epididymal sperm number and motility, as well as α-glucosidase activity in epididymis and histological analysis of testicular tissue, were determined after the i.p. treatment with lindane concentrations 9 a...
Article
Full-text available
Depending on the concentration, catecholamines activate various intracellular signaling pathways and can induce apoptosis in cardiac myocytes. Although 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide (JC-1) has been previously used to study mitochondria in intact cardiomyocytes, there have been no reports on the detection...
Article
Full-text available
A novel, disposable-bag bioreactor system that uses wave action for mixing and transferring oxygen was evaluated for BHK 21 C13 cell line growth and Aujeszky's disease virus (ADV) production. Growth kinetics of BHK 21 C13 cells in the wave bioreactor during 3-day period were determined. At the end of the 3-day culture period and cell density of 1.8...
Article
Full-text available
The alternatives to whole-animal testing include endpoint assays, cell and tissue cultures, use of tissue slices, toxicokinetic modelling, and structure-activity relationships and databases. The use of in vitro systems (subcellular fractions, cell lines, primary cell cultures, tissue slices, organ cultures, etc.) as research tools in toxicology is...
Article
Full-text available
The alternatives to whole-animal testing include endpoint assays, cell and tissue cultures, use of tissue slices, toxicokinetic modelling, and structure-activity relationships and databases. The use of in vitro systems (subcellular fractions, cell lines, primary cell cultures, tissue slices, organ cultures, etc.) as research tools in toxicology is...
Article
Full-text available
Production of Aujeszky's disease virus (ADV) from BHK 21 C13 suspension cells using a simple harvest and multiple harvest process mode was examined. We studied growth kinetics of BHK 21 C31 cells in 750 ml spinner flask containing 500 ml of culture medium. In the simple harvest process of ADV production, 425 ml of virus harvest was obtained with a...
Article
The effects of atrazine exposure on testicular sperm number, epididymal sperm number and motility and alpha-glucosidase activity in the epididymis were studied in Fischer rats. Histological changes in the testicular tissue were followed by light and electron microscopy. Groups of adult animals were treated i.p. with 60 and 120 mg atrazine kg(-1) bo...
Article
High density plating procedure was used to evaluate the effect of atrazine on anterior pituitary cells of rats in monolayer culture. Collagenase-dispersed pituitary cells plated in suspension with medium-199 and 10% foetal calf serum attached quantitatively to plastic surfaces within 24 hours. Electron microscopy showed subpopulations of different...
Article
Full-text available
High density plating procedure was used to evaluate the effect of atrazine on anterior pituitary cells of rats in monolayer culture. Collagenase-dispersed pituitary cells plated in suspension with medium-199 and 10% foetal calf serum attached quantitatively to plastic surfaces within 24 hours. Electron microscopy showed subpopulations of different...
Article
Full-text available
OBJECTIVE: To give more insight in the progesterone metabolism in rat after the treatment with the progestin ethynodiol diacetate. METHODS: Urinary excretion of the metabolites of subcutaneously administred (4-14C)-progesterone was studied in female rats. After an acid hydrolysis and extraction of urine the metabolites were analysed by thin layer c...
Article
Background and purpose: Activins as members of the transforming growth factor beta family of gene products are dimeric proteins isolated from follicular and testicular fluids and consists of two subunits linked by interchain disulfide bridges. They selectively stimulate pituitary cells in culture to secrete FSH, but not LH. The aim of this research...
Article
Following the informative regional development and environmental impacts in the Republic of Croatia, authors present the problems emphasized in environmental protection and health protection, and present the status of the contamination of food and drinking water in 1993. The level of education in the function of environmental protection in Croatia...
Article
The influence of s-triazine compounds (atrazine, prometryne and deethylatrazine) on testosterone conversion and 5 alpha-dihydrotestosterone-receptor complex formation was studied in vitro and in vivo in the rat prostate. A marked in vitro influence of atrazine and prometryne (from 0.465 to 1.392 mumol) and their mixtures (in total concentration, 0....
Article
The effects of subacute exposure to atrazine on body weight, ovarian cycling, conception rate and the size of litters in Fischer strain rats were studied. An atrazine dose of 120 mg kg-1 body wt given p.o. daily for 7 days to both female and male rats caused statistically significant loss of body weight in both sexes during the period of treatment....
Article
Full-text available
The metabolism of testosterone in the rat ventral prostate, anterior pituitary, basal hypothalamus and amygdala was studied in vitro under the influence of vitamin B6 compounds. The influence of these compounds on the activity of 5 alpha-reductase (5 alpha-R), 3 alpha- and 17 beta-hydroxysteroid dehydrogenase (3 alpha-HSD, 17 beta-HSD) was determin...
Article
Once entering the bloodstream, most toxic substances, including pesticides, can reach organs involved in the reproductive system. They can cross the placenta, as well as the brain barrier, posing various risks to the reproductive processes. The organochlorine insecticide lindane and the s-triazine herbicide atrazine produce changes in hormone-depen...
Article
The inhibitory influence of atrazine and deethylatrazine on testosterone metabolism in male rat anterior pituitary and hypothalamus were studied under in vivo and in vitro experimental conditions. In vivo strong influence of atrazine (12 mg/100 g by wt. daily during 7 days) on 5 alpha-R, 3 alpha- and 17 beta-HSD activities was detected in the anter...
Article
Daily s.c. injections of atrazine and deethylatrazine to rat mothers during pregnancy only or during pregnancy and lactation influenced the pituitary-gonadal axis of male and female offsprings. In female and male offspring, slow maturation of gonadotropic system is evident and as a consequence modified male and female pituitary 5 alpha-R activity i...
Article
The microcalorimetric method was used to study the specific reaction between 5α-dihydrotestosterone (5α-DHT), progesterone (P) and testosterone (T) with their receptors in the pituitary of male and female calves, at the age of 8–10 weeks. Experiments for measuring the binding affinity were performed at 37°C. Molar enthalpy changes for 5α-DHT are −9...
Article
Experiments were performed to study the effects of s-triazine herbicides, atrazine∗ and prometryne, on 5α-dihydrotestosterone (5α-DHT) receptor complex formation and on the activity of the 5α-reductase and 3α-hydroxysteroid dehydrogenase system in the anterior pituitary of male rats. By sucrose density gradient separation, it was found that in the...
Article
Through incubation with radioactive substrates, the in vitro activity of 17β-dehydrogenase (17-DHG) was studied in the testes of male and the pituitaries of both sexes of rats from birth to the 50th day of life, and the activity of 20 α-dehydrogenase (20-DHG) was studied in the ovaries of developing female rats and in females at parturition. Furthe...
Article
The effect of atratone, a selective s-triazine herbicide, on specific reactions in hypothalamus, pituitary and prostate gland was studied. It was found that atratone influenced the biosynthesis of LRF at the hypothalamic level. Increased concentrations of atratone from 2.5 to 8.0 mmol inhibited the synthesis of LRF from 22% to 94%. The presence of...
Article
Biosynthesis of peptides in vitro in male rat hypothalamic fragments wasinvestigated by incubating the tissue with 14C-labelled leucine, proline and glycine. Depending on the amino acid used, 4 or 6 labelled peptides were extracted from the tissue fragments with organic solvent mixture. The incorporation of the label into peptides was time dependen...
Article
The binding capacity of rat prostate cytosol for dihydrotestosterone, testosterone and progesterone was studied in vitro. The thermodynamic parameters obtained by microcalorimetry point to the importance of the observation of energy changes occuring during the hormone-receptor complex formation.
Article
The electrophoretic mobilities or ionic conductivities of 22Na+, 90Sr2+ and 36Cl– ions were measured electrophoretically at 25°C in aqueous solutions of NaCl, KCl, ½MgCl2, ½SrCl2, ½Na2SO4 and ½MgSO4, in the molar ratio 1:1:0.5:0.5:0.5:0.5, in the concentration range 0.1 to 4.0 mol dm–3 and in sea water of various salinities (from 3.77 to 36.45 part...
Article
The effects ofovariectomy. adrenalectomy and ovariectomy-adrenalectomy on 5α-reduction of testosterone and corticosterone by female rat tissues have been studied. The results suggest that separate enzymes are responsible for 5α-reduction of testosterone and corticosterone. Removal of ovaries or adrenal glands or both had no effect on 5α-reduction o...
Article
Binding enthalpies of various hormones to bovine serum albumin (BSA) and human serum albumin (HSA) in 50 mM phosphate buffer, pH 7.4, at 37 degrees C have been determined by direct microcalorimetry. The observed enthalpies of binding of progesterone, testosterone, dihydrotestosterone, corticosterone and estriol to BSA were found to be -13.24 plus o...
Article
Synthetic LH-RH was used to induce ovulation and pregnancy in 6 women with suspected hypothalamic anovulation. The women had been previously treated with Clomid, but according to indirect evidence this drug either failed to induce ovulation or the women had insufficient luteal phase. After treatment with LH-RH one pregnancy occurred and in 3 more c...
Article
Pituitary 5 alpha-reductase activity in intact male rats increases after the pituitary is incubated with the hypothalamus. Incubating the pituitary of castrate rats with the hypothalamus of intact rats relatively inhibits pituitary 5alpha-reductase activity. Coincubation of the pituitary and hypothalamus of castrate rats, or the pituitary of intact...
Chapter
This chapter discusses gas chromatographic determination of plasma testosterone. The gas chromatography procedure utilizes an instrument equipped with an electron capture detector. The major advantages that gas liquid chromatography (GLC) has over other analytical procedures are mainly the power of characterization, the separating power, the versat...
Article
Acetylation of the hydroxyl group in 20α-hydroxy-4--pregnen-3-one decreases the binding capacity of the molecule to transcortin to only 1% of that of progesterone. By this simple procedure it is possible to eliminate the influence of 20α-hydroxy-4-pregnen-3-one in determinations of progesterone concentrations by the competitive protein--binding met...
Article
Plasma corticosterone concentrations of female rats following adrenalectomy, adrenalectomy and ovariectomy, and adrenalectomy plus uterectomy were measured. On days 16 and 17 of normal pregnancy plasma corticosterone concentrations were 30% higher than in pregnant adrenalectomized females. Between days 18 and 21 of pregnancy plasma corticosterone c...
Article
Slices of rat pituitary gland, hypothalamus, amygdala, cerebral cortex and prostate have been incubated in vitro with labelled testosterone; the metabolites formed have been identified. Testosterone is convened into 17β-hydroxy-5α-androstan-3-one (androstanolone, dihydrotestosterone, DHT) by all tissues examined. The prostate is the structure which...
Article
Plasma levels of testosterone have been measured in adult male Sprague-Dawley rats using a gas-chromatographic procedure. Immediately after castration, the concentrations of testosterone in the plasma increase to reach a maximum one hour after orchidectomy; after this time a progressive decrease in plasma testosterone is observed. The concentration...

Questions

Question (1)
Question
5-alpha reductase in males is known to be involved in the conversion of testosterone at the 5-alpha dihydrotestosterone, which can bind to the specific androgen receptors responsible for the androgen activity of the males. 5-alpha reductase is also present in females, but until now without scientific explanation.

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