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PubMed1980

In vitro modeling of acute salpingitis caused by Neisseria gonorrhoeae.

Normal human fallopian tube organ culture was used as an in vitro model to study Neisseria gonorrhoeae infections. The effects of various gonococcal colony phenotypes on morphology of the epithelium were studied by scanning electron microscopy. After 30 minutes' incubation, there was striking attachment of piliated transparent phenotypes to the epithelium; however, there was no obvious pathology. After 24 hours' incubation, there were microcolony formation, slight swelling and hyperplasia of the mucosa, and occasional focal necrosis and sloughing of ciliated cells. Tissue from acute salpingitis showed widespread destruction of mucosa, hyperplasia, and crypt formation. Duplication of these findings in vitro may require longer incubation and the addition of other host factors.

Epithelium↗
PubMed2000

Valproate prevents epileptiform activity after trauma in an in vitro model in neocortical slices.

PURPOSE: Epileptogenesis is a hallmark of severe cortical trauma, with up to approximately 80% of patients experiencing seizures in the first 24 hours after penetrating head injury. An in vitro model of traumatic brain injury was developed to investigate hyperexcitability and epileptogenesis and their prevention. We determined whether sodium valproate would prevent epileptiform activity in this experimental model. METHODS: Rat cortical slices were prepared and maintained in vitro using standard methods. Trauma was effected by removing the superficial 450-500 microm of slices. Traumatized slices were exposed to valproate at various time points. Intracellular and extracellular recordings were used to assess evoked activities. RESULTS: In untreated traumatized deep segments, hyperexcitability was manifested by depressed inhibition and often (54%) by epileptiform activity. Preparations exposed to valproate at 30 minutes or later after trauma showed abnormal activity similar to control traumatized slices. Epileptogenicity in deep segments was significantly reduced when slices were exposed to valproate (a) continuously immediately after trauma, (b) after a 20-minute delay, or (c) immediately after trauma for 1 hour and then returned to physiological solution. Finally, slices that were exposed to valproate or pentobarbital beginning 20 minutes after trauma for only 1 hour and then returned to physiological medium showed a significant reduction in abnormal activity. Valproate was found to enhance fast gamma-aminobutyric acid(A)-ergic inhibitory strength. CONCLUSIONS: Valproate significantly reduces epileptiform activity after trauma to the neocortex, likely by restoring the excitation-inhibition balance, perhaps through augmentation of gamma-aminobutyric acid transmission. The timing of this action may have implications for mechanisms of seizure genesis and may suggest a role for rapid treatment.

Animals↗
PubMed1996

The hemodynamics of transjugular intrahepatic portosystemic shunts: investigations with Doppler sonography and development of an in vitro model.

RATIONALE AND OBJECTIVES: We evaluated Doppler sonography-based measurements of transjugular intrahepatic portosystemic shunt (TIPS) function and developed an in vitro model of normal TIPS hemodynamics. METHODS: We reviewed retrospectively the results of all trans-TIPS manometries (N = 116) performed during a 24-month period. Portosystemic pressure gradient was compared with peak stent velocity as measured by angle-corrected Doppler sonography. A flow phantom simulating TIPS was created using 8-, 10-, and 12-mm-diameter wire-mesh stents placed in cylindrical channels with lengths ranging from 3.4 to 6.0 cm. RESULTS: Among 50 trans-TIPS manometries with corresponding Doppler sonography performed on well-functioning shunts, measured portosystemic pressure gradient and peak velocity were not correlated (R2 = .014). On the basis of a regression of measurements in the flow phantom, pressure loss in a stented cylindrical channel was estimated as follows: delta p = rho.(0.145 -0.001.Rey + 0.816.L/D).(Vmean2/2), where rho is the fluid density, Rey is the Reynolds number, L is the channel length, D is the stent diameter, and Vmean is the time-averaged velocity within the stent. Predicted and measured pressure gradients were correlated (R2 = .91). CONCLUSION: Peak velocity in patients with a normally functioning TIPS does not predict the magnitude of the portosystemic pressure gradient.

Blood Flow Velocity↗
PubMed1989

Mechanical aspiration of hematomas in an in vitro model.

A modified Nucleotome (Surgical Dynamics, San Leandro, California) was used to aspirate blood clot in an in vitro model of intracerebral hematoma. This machine was successful in removing the clot at a reasonably rapid rate. It aspirates normal rat brain far more slowly. It therefore shows promise for being effective and safe in removing intracerebral hematomas in humans.

Adult↗
PubMed2006

A novel in vitro model to study staphylococcal biofilm formation on intraocular lenses under hydrodynamic conditions.

PURPOSE: To develop a novel in vitro model to study the formation of Staphylococcus epidermidis biofilm on intraocular lenses (IOLs) from the primary-attachment phase to the biofilm-accumulation phase. The model was designed to replicate intraocular conditions especially by taking into account intraocular hydrodynamics. METHODS: The model consisted of Tygon tubing connected to a vial containing acrylic hydrophobic IOLs. Three septa, placed along the tubing, allowed, respectively, the artificial aqueous humor's arrival and its elimination and the bacterial suspension's inoculation. A first pump allowed the aqueous humor's movement along the circuit, whereas a second one regulated the flow at which the nutritive environment was regenerated. The whole circuit was placed in a 34 degrees C water bath. Every 2 to 4 hours, lenses were taken from this environment. Bound bacteria were removed by scraping of optical faces and counted. All data are presented as the mean, SD, and coefficient of variation (CV). Comparisons among experiments were performed by one-way analysis of variance (ANOVA). RESULTS: Calculated CVs were close to 30, showing that biofilm formation was homogeneous. Differences between experiments were nonsignificant for each removal time. The model provided the full kinetics of S. epidermidis biofilm growth on acrylic hydrophobic IOLs, with a stationary phase reached after 28 hours of incubation. CONCLUSIONS: Biofilm development is modulated by many variables, including environmental factors. The findings in the present study of bacterial colonization of IOLs under intraocular physiological conditions allow understanding and more accurate targeting of biomedical device-related infections such as endophthalmitis.

Acrylic Resins↗
PubMed1998

A novel in vitro model to screen steroid 5 alpha-reductase inhibitors against benign prostatic hyperplasia.

A convenient and rapid in vitro model to screen steroid 5 alpha-reductase inhibitors, which are effective in the treatment of benign prostatic hyperplasia (BPH), was developed. In the presence of nicotinamide adenine dinucleotide phosphate (NADPH), steroid 5 alpha-reductase converts testosterone to dihydrotestosterone (DHT) which is a major etiologic factor of BPH. NADPH has characteristic absorbance at 340 nm, and the absorbance spectrum may be used to identify NADPH as a kind of the substrate in this enzymatic reaction. In this paper, NADPH, steroid 5 alpha-reductase, series concentration of testosterone and finasteride, and 4 ml Tris-HCl buffer were continuously incubated together at 37 degrees C and the NADPH OD values were continually measured. The descending rate of NADPH OD340nm value by linear regression from the beginning to the 10th minute is close to the initial velocity of the enzymatic reaction. The precise activity of the steroid 5 alpha-reductase was the slope after subtracting that of the blank control. The inhibition constant (Ki) of steroid 5 alpha-reductase inhibitors could be calculated according to the Lineweaver-Burk plots. Two drug screening models, the most common isotope model and the novel model, were compared in this paper. The result showed that the latter one is more economical, quicker and more effective than the former one.

5-alpha Reductase Inhibitors↗
PubMed1998

Interaction between alpha-MSH and gabaergic agents upon striatal cAMP levels: an in vitro model.

We have tried to investigate the possible interaction between the gabaergic system and alpha-MSH at a cellular level in an in vitro model of male albino rats tissue slices containing accumbens and caudate-putamen nuclei. Alpha-MSH alone increases cAMP levels, as does diazepam and phaclofen; however, these effects were blocked by SCH-23390. Both flumazenil and baclofen induced a decrease in the cAMP content. When both alpha-MSH and gabaergic agents were incubated together, cAMP levels were modified. It can be assumed that cAMP production by the neuropeptide and the gabaergic agents could be linked to the activation of dopaminergic D1 receptors. The latter receptors had no prominent effect on the interaction between alpha-MSH and the GABA agonists and antagonists. In summary, our results suggested that alpha-MSH and GABA system could be biochemically linked to produce a cellular effect.

Animals↗
PubMed2003

Establishing of two in vitro models of epithelial cells from the apocrine secreting rat coagulating gland.

Apocrine secretion is an alternative export pathway for proteins and was described especially for accessory sex glands of rodents and men. This mechanism is not as well characterized as the classical merocrine (eccrine) export. In the rat coagulating gland both secretion modes were observed, and several proteins were identified to be released by these two pathways. To obtain more data on the apocrine secretion mode, we established two culture models of the rat coagulating gland: primary epithelial cells and an organ culture system. The in vitro models were characterized with immunocytochemistry, electron microscopy and RT-PCR. The polarity of primary and passaged epithelial cells (passage 8) was proven by the detection of occludin, E-cadherin and beta-actin. The gland tissue pieces showed good maintenance after 1-week culture. Finally we demonstrated that the epithelial cells of both culture models are still expressing and producing apocrine and merocrine proteins. Using these two culture models for the rat coagulating gland, it is now possible to initiate studies on the apocrine secretion mechanism in vitro.

Animals↗
PubMed2001

Validation of a digital color Doppler flow measurement method for pulmonary regurgitant volumes and regurgitant fractions in an in vitro model and in a chronic animal model of postoperative repaired tetralogy of Fallot.

OBJECTIVES: The purpose of this study was to validate a digital color Doppler (DCD) automated cardiac flow measurement method for quantifying pulmonary regurgitation (PR) in an in vitro and a chronic animal model of the right ventricular outflow tract of postoperative tetralogy of Fallot (TOF). BACKGROUND: There has been no reliable ultrasound method that can accurately quantitate PR. METHODS: We developed an in vitro model of mild pulmonary stenosis and wide-open PR that mimics the patterns of flow seen in patients with postoperative TOF. Thirteen different forward and regurgitant stroke volumes (RSVs) across the noncircular shaped cross-sectional outflow tract flow area were estimated using the DCD method in two orthogonal planes. In six sheep with surgically created PR, 24 different hemodynamic states with PR strictly quantified by electromagnetic probes were also studied. RESULTS: The RSVs and regurgitant fractions (RFs) obtained by the DCD method using average values from two orthogonal planes correlated well with reference values (RSV: r = 0.99, mean difference = 0.02 +/- 0.39 ml/beat for in vitro model; r = 0.97, mean differences = 1.79 +/- 1.84 ml/beat for animal model, RF: r = 0.98, mean difference = -1.10 +/- 4.34% for in vitro model; r = 0.94, mean difference = 2.73 +/- 6.75% for animal model). However, the DCD method using a single plane had limited accuracy for estimating pulmonary RFs and RSVs. CONCLUSIONS: The DCD method using average values from two orthogonal planes provides accurate estimation of RSVs and RFs and should have clinical importance for serially quantifying PR in patients with postoperative TOF.

Animals↗
PubMed1993

Synergistic drug interactions of an HIV-1 protease inhibitor with AZT in different in vitro models of HIV-1 infection.

Synthetic peptide mimetic inhibitors of HIV-1 protease effectively block spread of infectious virus in acutely infected T-cells. These compounds also inhibit production of infectious virions from chronically infected T-cell lines. In order to determine the potential for drug interaction effects on antiviral activity, an HIV-1 protease inhibitor (SK&F 108922) and AZT were studied in three different in vitro models of HIV-1 infection of T-cell lines, specifically, (1) acutely infected cells infected at low multiplicity, (2) HIV-1 chronically-infected cells and (3) co-cultivations of chronically infected with non-infected cells. Upon co-treatment, these compounds demonstrated synergy in Molt4 or H9 cells acutely infected with HIV-1 strain IIIB. Either compound alone was a potent inhibitor of HIV-1 in co-cultivations of uninfected and chronically infected cells. In combination treatments of co-cultures, SK&F 108922 demonstrated strong synergy with AZT. Treatment of H9/IIIB chronically infected cells demonstrated no inhibitory effect by AZT treatment (EC50 = > 100 microM) whereas SK&F 108922 was inhibitory (EC50 = 3 microM). Upon co-treatment of H9/IIIB chronically infected cultures with both compounds, the antiviral activity was similar to that of the protease inhibitor alone suggesting no drug interaction. In the co-cultivation experiments, AZT's antiviral effect was most likely due to blocking spread of acute infection to uninfected cells in the culture. No antagonistic effects were observed with AZT and SK&F 108922 co-treatments. These results clearly demonstrate that an HIV-1 protease inhibitor can exert a potent antiviral effect on chronically infected T-cells in contrast to AZT and is capable of potent synergy with AZT in acute and co-culture in vitro infection models.

Acquired Immunodeficiency Syndrome↗
PubMed1993

An in vitro model of intra-epithelial expansion of transformed urothelial cells.

Replacement of normal urothelium by pre-cancerous epithelium may explain the high recurrence rate of human bladder cancer. An in vitro model was designed in order to study the mechanisms of expansion of transformed urothelial cells at the expense of normal urothelium. For this purpose, mouse bladder explants were allowed to expand on a transparent porous membrane. Subsequently, cell sheets of the non-tumorigenic mouse urothelial cell line NUC-5, the tumorigenic mouse urothelial cell line NUC-5 Py and the human bladder-carcinoma cell line T24 were inoculated adjacent to the primary explant. Daily measurements of the outgrowth of the bladder explant were performed, and all cultures were terminated on day 24. At this time the post-confluent primary urothelial cell outgrowths still showed proliferative activity, as demonstrated by bromodeoxyuridine incorporation. In due course the non-tumorigenic NUC-5 cells were replaced by the bladder outgrowth. T24 and NUC-5 Py cells were able to inhibit the bladder outgrowth, or even infiltrate or replace the explant. This was confirmed by immunohistochemistry with (species-specific) anti-cytokeratin antibodies and by microscopic evaluation of cross-sections of the porous membrane. This co-cultivation model appears to be suitable for the in vitro study of the mechanisms of intra-epithelial expansion of transformed urothelial cell lines.

Animals↗
PubMedDate not supplied

Primary culture of human lung microvessel endothelial cells: a useful in vitro model for studying Plasmodium falciparum-infected erythrocyte cytoadherence.

In the past, several cell lines have been used as in vitro models for studying cytoadherence, which refers to the specific binding of Plasmodium falciparum-parasitized red blood cells (PRBC) to host endothelium of microvessels. These models include: (a) human cells, including human umbilical vein endothelial cells (HUVEC), C32 amelanotic melanoma cells and monocytes; (b) non-human cells transfected with human genes, including COS and CHO cells; and (c) purified candidate receptor molecules. However, endothelial cells from malaria target organs are rarely investigated. In this study, we describe the efficient isolation and characterization of human lung endothelial cells (HLEC). This is the first in vitro study of P. falciparum PRBC cytoadherence to human lung endothelium, one of the target organs during severe malaria. The endothelial nature of the HLEC lines was confirmed by the presence of the von Willebrand factor, anti-human platelet endothelial adhesion molecule-1 and E-selectin antigens as specific endothelial markers. After exposure of HLEC to human cytokines, FACScan analysis indicated the coexpression of PRBC receptors CD36, intercellular adhesion molecule-1 (ICAM-1), E-selectin and vascular cell adhesion molecule-1 (VCAM-1). The laboratory-adapted P. falciparum strains adhered specifically in vitro to these HLEC. The binding of PRBC could be inhibited with variable efficiency by various monoclonal antibodies (anti-CD36 > anti-ICAM-1 > anti-VCAM-1 > anti-E-selectin). Target organ specific cell lines such as HLEC expressing a variety of potential P. falciparum PRBC cytoadherence receptors may provide in vitro systems for studying the pathophysiology of severe malaria and identifying new therapeutic agents designed to directly block adhesive events involved in severe malaria.

Animals↗
PubMed1999

Cardiac muscle tissue engineering: toward an in vitro model for electrophysiological studies.

The objective of this study was to establish a three-dimensional (3-D) in vitro model system of cardiac muscle for electrophysiological studies. Primary neonatal rat ventricular cells containing lower or higher fractions of cardiac myocytes were cultured on polymeric scaffolds in bioreactors to form regular or enriched cardiac muscle constructs, respectively. After 1 wk, all constructs contained a peripheral tissue-like region (50-70 micrometer thick) in which differentiated cardiac myocytes were organized in multiple layers in a 3-D configuration. Indexes of cell size (protein/DNA) and metabolic activity (tetrazolium conversion/DNA) were similar for constructs and neonatal rat ventricles. Electrophysiological studies conducted using a linear array of extracellular electrodes showed that the peripheral region of constructs exhibited relatively homogeneous electrical properties and sustained macroscopically continuous impulse propagation on a centimeter-size scale. Electrophysiological properties of enriched constructs were superior to those of regular constructs but inferior to those of native ventricles. These results demonstrate that 3-D cardiac muscle constructs can be engineered with cardiac-specific structural and electrophysiological properties and used for in vitro impulse propagation studies.

Aging↗
PubMed2003

Influence on fetal blood pH when adding amniotic fluid: an in vitro model.

OBJECTIVE: To assess the effect of contamination with amniotic fluid in different quantities on fetal capillary blood pH. DESIGN: In vitro model. SETTING: Department of Obstetrics, St Pölten Hospital. SAMPLE: Venous umbilical blood and amniotic fluid from 35 women who underwent amniotomy during labour. METHODS: Venous umbilical blood was mixed in vitro with amniotic fluid in diluted series (venous umbilical blood/amniotic fluid, 10:1 to 1:1). In every case two parallel runs of the dilution series in an inverted fashion were performed to rule out a possible time-dependent bias of the pH measurements. MAIN OUTCOME MEASURES: pH change in dilutions of umbilical venous blood with amniotic fluid: 10:1, +0.07 (0.02); 8:1, +0.08 (0.02); 6:1, +0.08 (0.03); 4:1, +0.07 (0.02); 2:1, +0.09 (0.03); 1:1, +0.12 (0.05); all P < 0.001. RESULTS: Amniotic fluid pH increases, whereas umbilical blood pH decreases slightly over time since collection. Dilutions of umbilical venous blood with amniotic fluid resulted in a significant pH rise. There was no significant difference between the two inversely performed dilution series. CONCLUSION: Amniotic fluid influences in vitro fetal venous blood pH immediately after contact. This observation indicates the possible masking of a fetus in distress by fetal scalp blood pH determination when amniotic fluid contaminates the sample.

Adult↗
PubMed1985

Advantages and disadvantages of an in-vitro model with two compartments connected by a dialyser: results of experiments with ciprofloxacin.

A two-compartment in-vitro model is described in which the compartments are separated by a hollow-fibre dialyser. It was used successfully to simulate the 2-compartment kinetics of intravenously administered ciprofloxacin and to observe the activity of ciprofloxacin against a strain of Serratia marcescens growing in the peripheral compartment. Because of the complexity of the apparatus, however, the experiments were labour-intensive, prone to break-down, and gave results only slowly. There was a possibility that drug-resistant variants were carried over from one experiment to the next by re-use of the dialyser. While the model could give very flexible kinetics and retained all of the culture, there were constraints on the variations in kinetics from the physical sizes of the compartments and practicable flow rates. An ever-present problem was the possibility of fluid diafiltering rapidly into either compartment. Such a model should perhaps only be used when a very short drug half-life is to be simulated or very flexible kinetics required. Simpler, multi-channel equipment could be more productive.

Anti-Bacterial Agents↗
PubMed1992

An in vitro model for studying the effects of slime and nonslime-forming Staphylococcus epidermidis contamination of intravenous catheters.

An in vitro model was developed to study the relationship between intravenous catheters, bacteria, and the subcutaneous tunnel. Studies of both slime-forming and nonslime-forming coagulase negative Staphylococcus epidermidis show that slime formation enhances capillary action of coagulase negative S. epidermidis. This offers a possible explanation of the increased virulence associated with slime-forming coagulase negative S. epidermidis in the clinical situation.

Agar↗
PubMed1996

PTCA in angulated segments: effects of balloon material, balloon length, and inflation sequence on straightening forces in an in vitro model.

We sought to determine the effect of balloon material, balloon length, and inflation sequence on the straightening forces generated during percutaneous transluminal coronary angioplasty (PTCA) in angulated segments. Using an in vitro model consisting of a curved channel (3/4" radius) with a displaceable pressure sensor, we examined four different balloon materials: compliant (POC), semicompliant (PE600 and Duralyn), and noncompliant (PET), two balloon lengths (20 mm and 40 mm), and two inflation sequences (rapid and slow) with continuous recording of straightening force during each balloon inflation. Three balloons were tested for each combination of materials, length, and inflation sequence. Long balloons exerted significantly lower straightening forces. There were significantly higher straightening forces with noncompliant, particularly short, balloons. Varying the inflation sequence had no significant effect. For PTCA in angulated segments: (1) long balloons produce lower straightening force, (2) noncompliant balloons produce higher straightening force, particularly with short balloons, and (3) varying the inflation sequence has no significant effect on straightening force.

Angioplasty, Balloon, Coronary↗
PubMed1980

An in vitro model for assessing optimum antibiotic dosage in urinary tract infection.

Experimental and clinical data from which dosage regimens can be rationally deduced are generally lacking. As an approach to this problem, an in vitro model of the urinary bladder has been constructed in which the conditions of exposure of bacteria to antibacterial drugs which exist in the treatment of cystitis are simulated. Results obtained so far correlate well with such clinical information as we possess and have helped to define more accurately the conditions which govern successful therapy of urinary infection. The most recent data suggest that much lower doses of some beta-lactam antibiotics than have been contemplated hitherto may be effective in the treatment of uncomplicated cystitis.

Anti-Bacterial Agents↗