PubMed Health⌕ Search

Biomedical subjects

T Kuczek

Publications and source records attributed to T Kuczek.

17 recordsLinked to original sources
PubMed2000

Cisplatin versus cisplatin combined with piroxicam in a canine model of human invasive urinary bladder cancer.

PURPOSE: More than 12,000 people are expected to die from invasive transitional cell carcinoma (TCC) of the urinary bladder each year in the United States, indicating that more effective therapy is needed. Drugs inhibiting cyclooxygenase (cox) have recently been found to have chemopreventive and antitumor activity and may potentiate the effects of chemotherapy. The purpose of this study was to determine whether cisplatin combined with the cox-inhibitor piroxicam would induce remission more frequently than cisplatin alone in a relevant animal model of human invasive TCC. METHODS: Pet dogs with naturally occurring, histopathologically confirmed, measurable TCC of the urinary bladder were randomized to receive cisplatin (60 mg/m2 i.v. every 21 days) or cisplatin (same dosage) combined with piroxicam (0.3 mg/kg orally every 24 h). Complete staging was performed prior to and at 6-week intervals during therapy. RESULTS: After eight dogs had been evaluated in each treatment group, a significant difference in remission rate was noted (Fisher's Exact test, P < 0.004). Tumor responses in the cisplatin/piroxicam group included two complete remissions (CR), four partial remissions (PR), two stable disease (SD), and no progressive disease (PD). Tumor responses to cisplatin alone in eight dogs were no CR, no PR, four SD, and four PD. Six additional dogs were treated with cisplatin/piroxicam, and in total 10 of 14 dogs had remission (two CR, eight PR). Renal toxicity of cisplatin/ piroxicam was frequent and dose limiting. CONCLUSIONS: Cisplatin/piroxicam induced remission more frequently than cisplatin alone in a canine model of human invasive TCC. Strategies to reduce renal toxicity need to be developed prior to evaluation of cisplatin/piroxicam in humans or general use of this treatment in pet dogs.

Animals↗
PubMed1998

Predictive models of carpal tunnel syndrome causation among VDT operators.

Carpal tunnel syndrome (CTS), a cumulative trauma disorder of the hand and wrist, is one of the most common disabling injuries experienced by video-display terminal (VDT) operators. The purpose of this study was to develop a theoretically based operational quantitative predictive model of the risk of work-related CTS among VDT operators. A total of 100 female VDT operators, who performed a variety of office functions, were studied at a major midwestern university. Data were collected on job exposure, anthropometry and posture factors using questionnaires, direct observation and video-recording. Discriminant analysis and logistic regression were performed to develop the operational models. The results of the study indicated the following: (1) percentage of workday working with a VDT was the most significant factor and accounted for 60% of the variance explaining the causation of musculoskeletal discomforts associated with CTS; (2) discriminant function with six variables (i.e. work duration, trunk incline, wrist extension, wrist ulnar deviation, overall anthropometric measure, weighted anthropometric measure) correctly classified 73% of the CTS group and 72% of the non-CTS group; (3) using the logistic regression model, the probabilities associated with changes in the predictive variables as affecting CTS risk are presented such that increasing the daily work duration from 1 h to 4 h increases the probability of CTS risk from 0.45 to 0.92. The results of the study suggest that the main causation of CTS is job design, the secondary (and lesser cause) is posture associated with the workplace design and the least contributing factor to CTS causation is the individual's anthropometric make-up.

Analysis of Variance↗
PubMed1996

Bicinchoninic acid protein assay in the determination of adriamycin cytotoxicity modulated by the MDR glycoprotein.

The development of simultaneous resistance to structurally unrelated drugs in cancer cells is a major obstacle to effective cancer chemotherapy. This multidrug-resistance (MDR) phenomenon is largely attributed to overexpression of a 170 kD glycoprotein, which serves as a transmembrane efflux pump in extruding a variety of natural anticancer drugs such as vinblastine, doxorubicin, and taxol from cancer cells. It is desirable, therefore, to discover compounds that can block the efflux mechanism and thus reverse drug resistance. The bicinchoninic acid protein assay has been adapted for use in a microtiter plate, into an easy, indirect method for screening MDR efflux blockers in plant extracts. This spectrophotometric assay is used to determine the enhancement of adriamycin cytotoxicity against resistant cancer cells by plant extracts or pure compounds indirectly. We have shown that the optical density measured (amount of cellular protein present) correlates with the number of viable cells and that fluorescence of Adriamycin associated with the cell correlates with the concentrations of Adriamycin added to the media. In addition, the relative efficacy of MDR reversal by various alkaloids has been determined.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Evaluation of in vitro cytotoxicity of nonsteroidal anti-inflammatory drugs against canine tumor cells.

Piroxicam and other nonsteroidal anti-inflammatory drugs (NSAID) have antitumor activity against naturally acquired cancer in dogs and human beings, and against experimentally induced tumors in rodents. We are investigating potential mechanisms of NSAID antitumor activity. The direct cytotoxicity of piroxicam indomethacin, and aspirin against 4 canine tumor cell lines (transitional cell carcinoma, squamous cell carcinoma, melanoma, and soft tissue sarcoma) was determined in short-term growth rate assays and in clonogenic assays. Piroxicam was evaluated alone and in combination with the lipoxygenase inhibitor zileuton, and in combination with the chemotherapeutic agents cisplatin and carboplatin. The 50% inhibitory concentrations (IC50) against melanoma cells in short-term growth rate assays were: 530 microM piroxicam, 180 microM indomethacin, and greater than 1 mM aspirin. These IC50 values were over 10 times greater than serum concentrations of these drugs that could safely be achieved in vivo. The IC50 of zileuton combined with piroxicam (280 microM) was not different from the IC50 of zileuton alone (230 microM; ANOVA P = 0.47) in melanoma cells. Similarly, addition of piroxicam did not alter the IC50 of either cisplatin (1.6 microM) or carboplatin (6.1 microM). These results suggest that NSAID, at serum concentrations achievable in vivo, do not have direct cytotoxicity against canine tumor cells tested. It is unlikely that the in vivo antitumor activity of NSAID is attributable to a direct cytotoxic effect.

Animals↗
PubMed1993

Persistence of cell cycle times over many generations as determined by heritability of colony sizes of ras oncogene-transformed and non-transformed cells.

The persistence of cell lifetimes during about 10 successive cell generations was investigated by comparing the number of cells in primary colonies and in secondary colonies derived from primary colonies. Primary colonies were grown from single cells for 3 or 4 days (a time equivalent to an average of five cell generations) and the number of cells in each primary colony determined. Cells in each primary colony were dispersed to initiate secondary colonies, grown for the same time, and the number of cells in secondary colonies determined. Several criteria were used to compare primary and related secondary colonies, the most informative was found to be regression and correlation coefficients between number of cells in primary colonies and mean numbers of cells in related secondary colonies. For two non-transformed mouse fibroblast cell lines, NIH 3T3 and BALB 3T3, the regression and correlation coefficients of cell number in primary and secondary colonies were positive. This suggests inheritance of cell lifetimes over many cell generations. After the addition of an activated ras oncogene (human cellular Harvey ras, or viral Kirsten ras) some regression and correlation coefficients changed in magnitude but all remained positive. Comparison of experimental data and the results of computer simulations suggest that several models of inheritance of cell lifetimes are not adequate to explain the results, including a model of independence between lifetimes of mother and daughter cells and the common model that describes daughter cells as inheriting the lifetime of their mother with deviation. Simulations do suggest that cell lifetimes are inherited within clones as deviation from the lifetime of the initial cell, and that the ras oncogene does not destroy persistence within clones but does increase heterogeneity of cell lifetimes.

3T3 Cells↗
PubMed1993

Analysis of aphidicolin-induced chromosome fragility in the domestic pig (Sus scrofa).

Aphidicolin (APC)-sensitive fragile sites were identified in chromosome preparations from peripheral lymphocyte cultures of 12 four-way crossbred pigs. A chi 2 analysis demonstrated that aphidicolin-induced breakage events and previously reported in vivo chromosome rearrangement events were not independent. Comparison of expected Poisson and negative binomial distributions to observed breakage patterns indicated that the negative binomial distribution provided a better fit to experimental data. The negative binomial distribution is consistent with a distribution of breakage rates, i.e., non-constant rates of breakage at chromosomal loci across the genome.

Animals↗
PubMed1993

Response of layer breeders to dietary acetylsalicylic acid. 3. Effects on fertility and hatchability of embryos exposed to control and elevated incubation temperatures.

Because acetylsalicylic acid (ASA, aspirin) is a common antipyretic drug, there has been considerable research on the effects of ASA on mammalian embryonic development. However, very limited research has been conducted on the effects of ASA on avian development and hatchability. The present study investigated the effect of dietary ASA on fertility and hatchability and whether embryos of breeder hens fed ASA, as compared with embryos of hens fed a control diet, would survive elevated temperatures during incubation. White Leghorn layer breeders were fed 0, .025, .050, .100, .200, and .400% ASA for the first 13 mo of egg production. When averaged over 13 mo, hens fed .40% dietary ASA demonstrated a decline in fertility (P < .03), hatchability of fertile eggs (P < .04), and hatchability of eggs set (P < .02). Chicks from hens fed .10% ASA weighed more than chicks from hens receiving 0, .025, .20, or .40% ASA (P < .01). When embryos were incubated at elevated temperatures of 42.8 or 43.3 C for 5.5 to 12 h on Day 16 of incubation, hatchability declined. Also, ASA fed to layer breeders did not improve hatchability of embryos exposed to elevated incubation temperatures when compared with embryos exposed to a control incubation temperature (37.2 C). During Month 9 of production, chicks from hens fed .05 and .10% ASA and exposed to an elevated temperature of 42.8 C for 9 h on Day 16 of incubation weighed more than similarly heat-stressed chicks of hens fed 0, .20, or .40% ASA (temperature by diet interaction, P < .03).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Mechanism-based model for tumor drug resistance.

The development of tumor resistance to cytotoxic agents has important implications in the treatment of cancer. If supported by experimental data, mathematical models of resistance can provide useful information on the underlying mechanisms and aid in the design of therapeutic regimens. We report on the development of a model of tumor-growth kinetics based on the assumption that the rates of cell growth in a tumor are normally distributed. We further assumed that the growth rate of each cell is proportional to its rate of total pyrimidine synthesis (de novo plus salvage). Using an ovarian carcinoma cell line (2008) and resistant variants selected for chronic exposure to a pyrimidine antimetabolite, N-phosphonacetyl-L-aspartate (PALA), we derived a simple and specific analytical form describing the growth curves generated in 72 h growth assays. The model assumes that the rate of de novo pyrimidine synthesis, denoted alpha, is shifted down by an amount proportional to the log10 PALA concentration and that cells whose rate of pyrimidine synthesis falls below a critical level, denoted alpha 0, can no longer grow. This is described by the equation: Probability (growth) = probability (alpha 0 less than alpha-constant x log10 [PALA]). This model predicts that when growth curves are plotted on probit paper, they will produce straight lines. This prediction is in agreement with the data we obtained for the 2008 cells. Another prediction of this model is that the same probit plots for the resistant variants should shift to the right in a parallel fashion. Probit plots of the dose-response data obtained for each resistant 2008 line following chronic exposure to PALA again confirmed this prediction. Correlation of the rightward shift of dose responses to uridine transport (r = 0.99) also suggests that salvage metabolism plays a key role in tumor-cell resistance to PALA. Furthermore, the slope of the regression lines enables the detection of synergy such as that observed between dipyridamole and PALA. Although the rate-normal model was used to study the rate of salvage metabolism in PALA resistance in the present study, it may be widely applicable to modeling of other resistance mechanisms such as gene amplification of target enzymes.

Animals↗
PubMed1991

Effect of sampling interval on serum concentrations of luteinizing hormone, follicle-stimulating hormone, and prolactin in prepubertal, ovariectomized, and cycling gilts.

Three experiments were conducted to determine the effect of sampling interval on serum concentrations of LH, FSH, and prolactin (PRL) in prepubertal, ovariectomized, and cycling gilts. In all experiments, blood samples were drawn at 2-min intervals for 4 h from indwelling jugular catheters. Mean serum hormone concentrations, mean number of peaks, and mean and maximum peak heights of LH, FSH, and PRL were calculated using values reflecting 2-, 6-, 10-, 20-, 30-, and 60-min sampling intervals. For LH, FSH, and PRL, mean serum concentrations can be obtained through blood samples drawn at hourly intervals. Since LH peaks are very distinct in pigs, the number of secretory peaks and mean peak height can be obtained via samples drawn at 20-min intervals. Since FSH and PRL peaks are less well defined, a more frequent sampling interval (10 min) is needed to determine number of peaks and mean peak height. To obtain the maximum peak height or the number of minutes for LH, FSH, or PRL to rise from its nadir to zenith, blood samples need to be drawn at 2-min intervals. Regardless of reproductive state, these data indicate that the sampling interval needed to characterize serum concentrations of LH, FSH, and PRL in the gilt is dependent upon the parameter in question.

Animals↗
PubMed1987

Tumor cell heterogeneity: divided-colony assay for measuring drug response.

In vitro tests for predicting the response of tumors to chemotherapeutic agents might be improved if they were modified to take into account tumor-cell heterogeneity. We have studied the heterogeneity of cellular growth rate and drug response in mouse fibroblast NIH 3T3 cells and in NIH 3T3 cells transformed with the human HRAS gene (homologue of the Harvey sarcoma virus oncogene v-Ha-ras) from the EJ human bladder carcinoma cell line. Growth-rate heterogeneity was detected as a broad distribution of numbers of cells per colony. In spite of this heterogeneity, secondary colonies have numbers of cells per colony that resemble that of the primary colony from which they were derived. The variance between unrelated secondary colonies is increased by HRASEJ. Colony-size measurements are reliable because primary colonies divided in half formed two groups of secondary colonies (on two separate plates) that had indistinguishable mean colony sizes. Based on these observations, a divided-colony procedure was devised to detect the drug response of heterogeneous cell populations. Primary colonies are divided into two groups of cells, one of which is treated with a drug and the other is left untreated as a control. The size distribution of treated secondary colonies is then compared to that of the untreated control and to that of the primary colony from which it was derived. The divided-colony procedure is proposed as a modification of the human-tumor-cloning system to increase the sensitivity and reliability of in vitro procedures used to determine the drug response of heterogeneous tumor-cell populations.

Animals↗
PubMed1985

Use of the average antibody-antigen bond concept and probability theory to simplify modeling of linear and circular antibody-antigen complex formation.

We illustrate use of a simple approach to describe the equilibrium interactions of mixtures of monoclonal antibodies and antigens. This procedure is based on elementary concepts in probability theory and is readily suited to describing interactions of antibodies and antigens which form circular as well as linear complexes. The method is also suited to describing the inhibitory effects of antibodies which compete for overlapping epitopes and an example is provided to show how the procedure can be used to describe the interactions of antibodies which inhibit circular complex formation. We also outline simple strategies for preparing computer programs to simulate binding of antigens to defined antibody mixtures. The methods described should facilitate design of immunoassay procedures based on the use of defined mixtures of monoclonal antibodies.

Antibodies, Monoclonal↗
PubMed1985

Potential of a quantal response as a mechanism for oscillatory behavior: implications for our concepts of hormonal control mechanisms.

This article describes the potential of a quantal (i.e., all-or-none) response as a model for understanding the interactions between endocrine, paracrine and autocrine hormones. We review the general features of continuous and discontinuous (i.e., oscillating) quantal models including the role of a threshold. In addition, we also describe a few of the many different biochemical mechanisms which may give rise to quantal behavior. One of the more attractive schemes involves the coordinate regulation of opposing biochemical pathways resulting from phosphorylation of hormone receptors and/or rate-limiting enzymes. At least one hormone receptor (i.e., that for insulin) and many rate-limiting enzymes which control the flow of metabolites through a variety of metabolic pathways can be phosphorylated at multiple sites by one or more protein kinases. Phosphorylation may enhance or inhibit the activities of these proteins depending on which sites are modified. Furthermore, since phosphorylation of some sites on a protein may enhance the ability of phosphoprotein phosphatases to dephosphorylate other sites responsible for biological activity of the protein, phosphorylation also has the potential to produce a discontinuous quantal response. Quantal response mechanisms may alter our notions of endocrine regulation. When a quantal response mechanism is applied to a simple negative feedback model similar to that which was originally postulated to explain the interactions between gonadotropin and steroid hormonal levels, the model can account for the oscillations in hormone levels even when the input is constant. Conversely, when a graded mechanism is applied to the same negative feedback model, the model will almost certainly result in constant hormone levels. Further, the model illustrates that small changes in rate constants and thresholds of response, amplification of hormonal signals, and degradation of intermediate regulators can produce large shifts in the output of the system. These may account for the variability in hormonal levels observed in some endocrine systems. Finally, the high sensitivity of the quantal response mechanism accounts for the data which suggest that gonadotropins may play permissive rather than causal roles in regulation of gonadal function. Since increasing evidence suggests that all cells of a given type may not be equal in terms of hormonal responsiveness, measurements of response in single cells over short time periods will be needed before the role of a quantal response can be determined and endocrine regulation will be fully understood.

Animals↗
PubMedDate not supplied

Omega-3 fatty acids in boys with behavior, learning, and health problems.

The purpose of the study reported here was to compare behavior, learning, and health problems in boys ages 6 to 12 with lower plasma phospholipid total omega-3 or total omega-6 fatty acid levels with those boys with higher levels of these fatty acids. A greater frequency of symptoms indicative of essential fatty acid deficiency was reported by the parents of subjects with lower plasma omega-3 or omega-6 fatty acid concentrations than those with higher levels. A greater number of behavior problems, assessed by the Conners' Rating Scale, temper tantrums, and sleep problems were reported in subjects with lower total omega-3 fatty acid concentrations. Additionally, more learning and health problems were found in subjects with lower total omega-3 fatty acid concentrations. (Only more colds and more antibiotic use were reported by those subjects with lower total omega-6 fatty acids). These findings are discussed in relation to recent findings for omega-3 experimentally deprived animals.

Child↗
PubMedDate not supplied

Piroxicam therapy in 34 dogs with transitional cell carcinoma of the urinary bladder.

Thirty-four dogs with histopathologically confirmed, measurable, nonresectable transitional cell carcinoma of the urinary bladder were treated with piroxicam (0.3 mg/kg PO sid) and were evaluated for tumor response and drug toxicity. Dogs were evaluated at the Purdue University Veterinary Teaching Hospital by means of physical examination, thoracic and abdominal radiography, cystography, complete blood count, serum biochemistry profile, and urinalysis. In selected cases, prostaglandin E2 (PGE2) concentrations in plasma and in supernatants of stimulated monocytes, and natural killer cell activity were quantified. Dogs were evaluated before therapy and at 28 and 56 days after initiation of therapy. Dogs with stable disease or remission at 56 days remained on the study and were evaluated at 1 to 2 months intervals. Tumor responses were 2 complete remissions, 4 partial remissions, 18 stable diseases, and 10 progressive diseases. The median survival of all dogs was 181 days (range, 28 to 720+ days), with 2 dogs still alive. Piroxicam toxicity consisted of gastrointestinal irritation in 6 dogs and renal papillary necrosis (detected at necropsy) in 2 dogs. Monocyte production of PGE2 appeared to decrease with therapy in dogs whose tumors were decreasing in size, and increased in dogs with tumor progression. A consistent pattern in natural killer cell activity was not observed. In vitro cytotoxicity assays against 4 canine tumor cell lines revealed no direct antitumor effects of piroxicam. In summary, antitumor activity, which was not likely the result of a direct cytotoxic effect, was observed in dogs with transitional cell carcinoma of the bladder treated with piroxicam.

Administration, Oral↗
PubMedDate not supplied

High urine concentrations of basic fibroblast growth factor in dogs with bladder cancer.

Because dogs with bladder cancer often have advanced disease at the time of diagnosis, the identification and use of a tumor marker that could facilitate earlier diagnosis is a valid approach to improve prognosis. The objective of this study was to determine if urine concentrations of the proangiogenic peptide, basic fibroblast growth factor (bFGF), are high in dogs with bladder cancer compared with normal dogs and dogs with urinary tract infection. We used a commercially available enzyme-linked immunosorbent assay test kit to quantitate bFGF in the urine of 17 normal dogs, 10 dogs with urinary tract infection, and 7 dogs with locally active transitional cell carcinoma of the urinary bladder. In normal dogs, the median urine bFGF concentration was 2.23 ng/g creatinine (quartile range, 1.53 to 5.12 ng/g creatinine). The median urine bFGF concentration in dogs with urinary tract infection did not differ significantly from normal dogs. Dogs with bladder cancer had significantly higher urine bFGF concentrations than normal dogs (P < .002) and dogs with infection (P < .02). The median urine bFGF concentration in dogs with transitional cell carcinoma was 9.86 ng/g creatinine (quartile range, 7.40 to 21.63 ng/g creatinine). Six of 7 dogs with bladder cancer had urine bFGF concentrations that were up to 7.4 times the 90th percentile value for normal dogs. Only 1 of 10 dogs with infection had a urine bFGF concentration that exceeded the 90th percentile of normal. These data suggest that canine bladder cancers export bFGF, and that urine bFGF may be useful as a diagnostic tumor marker or noninvasive indicator of treatment response.

Animals↗
PubMedDate not supplied

Phase II clinical trial of carboplatin in canine transitional cell carcinoma of the urinary bladder.

Fourteen dogs with histologically-confirmed transitional cell carcinoma (TCC) of the urinary bladder were treated with 300 mg/m2 carboplatin every 3 weeks. Response to therapy was assessed with abdominal radiography, double contrast cystography, urinary bladder ultrasonography and thoracic radiography before therapy and at 6-week intervals during therapy. Dogs were monitored for hematologic toxicity with a CBC and platelet count performed immediately before and 10 to 14 days after carboplatin treatment. Tumor responses included progressive disease in 11 dogs and stable disease in 1 dog. Two dogs were euthanized due to carboplatin toxicity before assessment of tumor response. Toxicity included thrombocytopenia with or without neutropenia in 7 dogs and gastrointestinal toxicity in 6 dogs. Carboplatin therapy was not beneficial in the treatment of TCC in the 14 dogs in this study.

Animals↗