The isolated perfused equine distal limb as an ex vivo model for pharmacokinetic studies

Even though intra-articular injections play an important role in the treatment of joint-related lameness in horses, little is known about pharmacokinetic properties of substances used. Therefore, an ex vivo model for pharmacokinetic studies was developed using distal forelimbs of slaughtered horses. The extremity was perfused with gassed Tyrode solution for up to 8 h. Tissue viability was confirmed by measurements of glucose consumption, lactate production, and lactate dehydrogenase activity in the perfusate. Standard criteria for tissue viability had been determined in preliminary experiments (n = 11), which also included histological examinations of the joint capsule. As the model's first implementation, the articular efflux rate of betamethasone (BM), administered as BM disodium phosphate intra-articularly to the fetlock joint (4 mg BM/joint), was investigated. The concentration of BM in the venous perfusate of the radial vein was measured by means of high-performance liquid chromatography. The average BM efflux rate per minute was calculated to be 5.1 μg/min with values ranging from 9 μg/min to 2.9 μg/min. 7.5 h after i.a. application, 2.3 mg BM had left the joint via the radial vein. Using this inexpensive setup, the presented model allows studying a variety of pharmacological topics without the ethical limitations of animal studies.

Exploring optimal current stimuli that provide membrane voltage tracking in a neuron model

Studying neurons from an energy efficiency perspective has produced results in the research literature. This paper presents a method that enables computation of low energy input current stimuli that are able to drive a reduced Hodgkin-Huxley neuron model to approximate a prescribed time-varying reference membrane voltage. An optimal control technique is used to discover an input current that optimally minimizes a user selected balance between the square of the input stimulus current (input current 'energy') and the difference between the reference voltage and the membrane voltage (tracking error) over a stimulation period. Selecting reference signals to be membrane voltages produced by the neuron model in response to common types of input currents i(t) enables a comparison between i(t) and the determined optimal current stimulus i*(t). The intent is not to modify neuron dynamics, but through comparison of i(t) and i*(t) provide insight into neuron dynamics. Simulation results for four different bifurcation types demonstrate that this method consistently finds lower energy stimulus currents i*(t) that are able to approximate membrane voltages as produced by higher energy input currents i(t) in this neuron model.

[Protein S3 fragments neighboring mRNA during elongation and translation termination on the human ribosome]

Protein S3 fragments were determined that crosslink to modified mRNA analogues in positions +5 to +12 relative to the first nucleotide in the P-site binding codon in model complexes mimicking states of ribosomes at the elongation and translation termination steps. The mRNA analogues contained a Phe codon UUU/UUC at the 5'-termini that could predetermine the position of the tRNA(Phe) on the ribosome by the location of P-site binding and perfluorophenylazidobenzoyl group at a nucleotide in various positions 3' of the UUU/UUC codon. The crosslinked S3 protein was isolated from 80S ribosomal complexes irradiated with mild UV light and subjected to cyanogen bromide-induced cleavage at methionine residues with subsequent identification of the crosslinked oligopeptides. An analysis of the positions of modified oligopeptides resulting from the cleavage showed that, in dependence on the positions of modified nucleotides in the mRNA analogue, the crosslinking sites were found in the N-terminal half of the protein (fragment 2-127) and/or in the C-terminal fragment 190-236; the latter reflects a new peculiarity in the structure of the mRNA binding center in the ribosome, unknown to date. The results of crosslinking did not depend on the type of A-site codon or on the presence of translation termination factor eRF1.

Associates of change in liver fat content in the morbidly obese after laparoscopic gastric banding surgery

AIM

Hepatic steatosis affects up to 30% of the population. After weight loss, monitoring of the change in hepatic steatosis is not routinely performed. This study aimed to define the closest associates of change in liver fat content in a population of obese females following laparoscopic gastric banding surgery.

METHODS

Before and 3 months after surgery, proton magnetic resonance spectroscopy and magnetic resonance imaging were used to estimate the amount of lipid contained within the liver and abdominal subcutaneous and visceral compartments of 29 obese [mean body mass index (BMI) 39 +/- 5 kg/m(2)], non-diabetic women aged between 20 and 62 years. Liver enzymes, fasting plasma glucose and insulin were also measured as well as body weight, BMI and waist circumference. Insulin sensitivity was estimated using homeostasis model assessment insulin resistance index.

RESULTS

Significant reductions occurred in body weight (p < 0.001), abdominal fat volumes (p < 0.001) and liver fat (p = 0.037) 3 months after surgery. Change in liver fat content more closely associated with change in serum gamma-glutamyl transferase (GGT; r = 0.71, p < 0.001) than with changes in weight (r = 0.10, p = 0.612) and waist circumference (r = 0.15, p = 0.468).

CONCLUSIONS

Our findings suggest that obese non-diabetic female patients who have undergone significant weight loss over 3 months can be better assessed for the regression of excess liver fat content by monitoring changes in serum GGT levels rather than changes in simple anthropometry.

Renal prothrombin mRNA is significantly decreased in a hyperoxaluric rat model of nephrolithiasis

Although urinary prothrombin fragment 1 (UPTF1) possesses several hallmarks expected of a regulatory protein in urolithiasis, its precise role remains unknown. To determine the relationship between renal prothrombin (PT), the parent molecule of UPTF1, and lithogenesis, this study quantified and compared levels of renal PT mRNA in healthy rats (n = 10) and rats rendered lithogenic (n = 10) by ingestion of 0.75% ethylene glycol for 8 weeks. Studies included morphological and histological examination of the kidneys with scanning electron microscopy of the urinary filtrates of control and experimental animals. Haematuria and calcium oxalate (CaOx) crystals occurred in the urine of all experimental rats, but not in those of controls. Histological examination showed birefringent nephroliths and associated damage in kidneys of lithogenic rats, which were not seen in the control group. The amounts of total RNA extracted from both groups of rats were similar, but the median ratio of PT to beta-actin transcript of 11.14 x 10(-4) (10.65 x 10(-4) +/- 2.24 x 10(-4)) in the control rats was significantly (p < or = 0.001) reduced to 6.47 x 10(-4) (6.57 x 10(-4) +/- 2.72 x 10(-4)) in the lithogenic group. These results demonstrate that renal PT mRNA is reduced by approximately 42% in lithogenic rats and confirm the existence of a direct association between renal PT synthesis and calculogenesis. Attempts to compare renal PT and urinary levels of PTF1 were unsuccessful because of interference from hepatic PT circulating in the blood, haematuria, and the presence of urinary CaOx crystals. This is the first report of a significant reduction in the renal expression of a urinary protein well documented to inhibit CaOx crystal growth and aggregation in undiluted human urine in vitro.

Apolipoprotein-D: a novel cellular marker for HGPIN and prostate cancer

BACKGROUND

High grade prostatic intraepithelial neoplasia (HGPIN) is a putative pre-malignant lesion of the prostate. While apolipoprotein-D (Apo-D), an androgen-regulated hydrophobic transporter protein, is expressed in prostate tumors, its expression in HGPIN is unknown.

METHODS

Immunoreactivity for Apo-D and another androgen-regulated protein, prostate specific antigen (PSA), was investigated in 64 radical prostatectomy tissues by video image analysis.

RESULTS

Eighty two percent of prostatectomy specimens demonstrated moderate to strong Apo-D immunoreactivity in areas of HGPIN. In comparison, weak Apo-D immunoreactivity was observed in non-malignant areas in only 24% of specimens. The median (range) percentage cellular area of HGPIN immunopositive for Apo-D (9.7%, 0-42.9), and the cellular concentration of Apo-D (MIOD 3.1, 0-13.3), were intermediate between that of normal (area 0%, 0-53.5%, MIOD 0, 0-12.6) and early stage prostate cancer tissues (area 29.2%, 0-90.8%, MIOD 6.7, 0-28.1). This increase in Apo-D expression from non-malignant, through HGPIN to prostate cancer was statistically significant (P < 0.001), and contrasted with the decrease observed in PSA staining between adjacent areas of normal glands, HGPIN, and cancer (P = 0.026).

CONCLUSIONS

The presence of high levels of immunoreactive Apo-D in HGPIN and prostate cancer, but not in non-malignant epithelial cells, is consistent with HGPIN being an intermediate lesion in the transition to prostate cancer, and suggests that cellular Apo-D expression is a marker of malignant transformation of the prostate.

CAT administration of language placement examinations

This article describes the development of a computerized adaptive test for Cegep de Jonquiere, a community college located in Quebec, Canada. Computerized language proficiency testing allows the simultaneous presentation of sound stimuli as the question is being presented to the test-taker. With a properly calibrated bank of items, the language proficiency test can be offered in an adaptive framework. By adapting the test to the test-taker's level of ability, an assessment can be made with significantly fewer items. We also describe our initial attempt to detect instances in which "cheating low" is occurring. In the "cheating low" situation, test-takers deliberately answer questions incorrectly, questions that they are fully capable of answering correctly had they been taking the test honestly.

[Telemedicine in pediatric oncology]

The telemedicine project of the Competence Net Pediatric Oncology of the German/Austrian Gesellschaft für Pädiatrische Onkologie und Hämatologie (GPOH) has as an initial step of its work-programme sent out a questionnaire to the 54 largest pediatric hematology/oncology units in Germany. Institutions were asked for their experience, motivation, existing infrastructure, and anticipated benefits and obstacles regarding the implementation of telemedicine in patient care and research. Of the 54 largest German Pediatric Oncology institutions asked, 46 completed the questionnaire (85 %).

RESULTS

1. The need for further detailed information on implementation and for help in technical realization of telemedicine applications was expressed by all participants. 2. The majority expected practical advantages from telemedicine communication and anticipated that telemedicine will increase quality in treating children with cancer. 3. Expert consultation (study chairman, reference radiologists) is stated as to be most important. 4. Thirty-three of 46 physicians (72 %) believe that telemedicine will reduce costs in medical care within the next years. 5. It is anticipated that the introduction of telemedicine is time consuming. 6. The lack of available medical informatics competence and manpower was regarded as the most important obstacle. 7. Data security and standardization, transfer speed and transmission quality are considered most important. 8. Most of the institutions (91 %) use computers in the management of patients. Fourty-four (96 %) are connected to the Internet. 9. Thirty-seven of 46 institutions were prepared to invest in the implementation of telemedicine. This analysis demonstrates that the use of telemedicine is expected to become standard in pediatric oncology, while the existing infrastructure and status of information regarding this subject at present are insufficient. The most pressing practical need for telemedicine applications is seen in the field of electronic expert consultation. Hence, the Telemedicine-Project of the GPOH Competence Net will focus on this aspect first.

Evaluation of a waterless, scrubless chlorhexidine gluconate/ethanol surgical scrub for antimicrobial efficacy

A new waterless surgical hand preparation containing 1% chlorhexidine gluconate (CHG) and 61% ethyl alcohol was evaluated for antimicrobial efficacy in comparison with a standard 4% CHG surgical scrub and a 61% ethyl alcohol control. Clinical studies were based on the Tentative Final Monograph for Health-Care Antiseptic Drug Products (TFM) (proposed rule) and the Standard Test Method for Evaluation of Surgical Hand Scrub Formulations (ASTM E1115-91). Two randomized, blinded, well-controlled clinical studies involving 137 healthy subjects were conducted to evaluate the antimicrobial effectiveness of the CHG/ethanol hand preparation in producing an immediate and persistent reduction in the normal bacterial flora of the hands. The CHG/ethanol hand preparation was applied without scrubbing or the use of water, and a standard 4% CHG reference product was applied with a scrub brush in 2 traditional 3-minute surgical scrubs. In 1 study, a 61% ethanol vehicle control treatment was applied without scrubbing or use of water. During a 5-day period, each study subject performed a series of 11 surgical scrubs with 1 of the test treatments. After the first treatment on days 1, 2, and 5, surgical gloves were worn for 3 or 6 hours. Bacterial samples were taken with the glove-juice technique at 1 minute, 3 hours, and 6 hours after treatment. The immediate bactericidal effect of the CHG/ethanol hand preparation after a single application resulted in a 2.5-log reduction in normal flora. This bactericidal effect persisted throughout the studies and eventually increased to a 3.6-log reduction after the 11th scrub on day 5. The log reductions of the CHG/ethanol hand preparation proved to be significantly better (P <.05) than that of the 4% CHG product at each sampling interval on days 1 and 2 and the sampling at 6 hours on day 5 and significantly better than the 61% ethanol vehicle at all times. The combination of 1% CHG and 61% ethanol had significantly greater microbial reduction than either the 4% CHG (without ethanol) or the 61% ethanol vehicle (without CHG).

Apoptosis in neonatal murine lung exposed to hyperoxia

Exposure to high concentrations of oxygen in the neonatal period may impair lung growth and is a major contributing factor to the development of bronchopulmonary dysplasia. Cell death from hyperoxic injury may occur through either an apoptotic or nonapoptotic pathway, and we were interested in determining the type of cell death that occurs in the lung of neonatal mice exposed to hyperoxia. We found increased levels of Bax messenger RNA, a gene associated with apoptosis, in the lungs of neonatal mice born and raised in 92% hyperoxia. We next determined the extent of apoptosis taking place in the lungs of neonatal mice exposed to hyperoxia using terminal deoxyribonucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling in 3.5-, 4.5-, and 5.5-d-old neonatal lung. The number of apoptotic cells in peripheral lung was significantly higher in the 3.5-, 4.5-, and 5.5-d-old mice treated with oxygen compared with that in the room-air control mice. Further, the number of apoptotic cells in the lung increased with longer exposure duration. In murine lung bronchus cells exposed to hyperoxia, growth arrest occurred after 48 h of oxygen exposure. Using annexin V binding, necrotic cell death was found to be the major form of cell death in these cells after 72 h of hyperoxic exposure. We conclude that 92% hyperoxia causes significant lung injury in neonatal mice exposed to hyperoxia, and that the number of apoptotic cells in the lung increases the longer the duration of exposure. The increase in apoptosis from hyperoxic exposure during a critical period of lung development may be an important factor in the impaired lung growth and remodeling that occur in animals exposed to high oxygen concentrations. Finally, it appears that hyperoxic injured cells in neonatal lung undergo both apoptotic and nonapoptotic cell death.

Signal transducer gp130: biochemical characterization of the three membrane-proximal extracellular domains and evaluation of their oligomerization potential

Glycoprotein 130 (gp130) is a type I transmembrane protein and serves as the common signal-transducing receptor subunit of the interleukin-6-type cytokines. Whereas the membrane-distal half of the gp130 extracellular part confers ligand binding and has been subject to intense investigation, the structural and functional features of its membrane-proximal half are poorly understood. On the basis of predictions of tertiary structure, the membrane-proximal part consists of three fibronectin-type-III-like domains D4, D5 and D6. Here we describe the bacterial expression of the polypeptides predicted to comprise each of these three domains. The recombinant proteins were refolded from solubilized inclusion bodies in vitro, purified to homogeneity and characterized by means of size-exclusion chromatography and CD spectroscopy. For the first time the prediction of three individual membrane-proximal protein domains for gp130 has been verified experimentally. The three domains do not show intermediate-affinity or high-affinity interactions between each other. Mapping of a neutralizing gp130 monoclonal antibody against D4 suggested a particular functional role of this domain for gp130 activation, because above that an intrinsic tendency for low-affinity oligomerization was demonstrated for D4.

Ribosomal protein S5 interacts with the internal ribosomal entry site of hepatitis C virus

Translational initiation of hepatitis C virus (HCV) genome RNA occurs via its highly structured 5' noncoding region called the internal ribosome entry site (IRES). Recent studies indicate that HCV IRES and 40 S ribosomal subunit form a stable binary complex that is believed to be important for the subsequent assembly of the 48 S initiation complex. Ribosomal protein (rp) S9 has been suggested as the prime candidate protein for binding of the HCV IRES to the 40 S subunit. RpS9 has a molecular mass of approximately 25 kDa in UV cross-linking experiments. In the present study, we examined the approximately 25-kDa proteins of the 40 S ribosome that form complexes with the HCV IRES upon UV cross-linking. Immunoprecipitation with specific antibodies against two 25-kDa 40 S proteins, rpS5 and rpS9, clearly identified rpS5 as the protein bound to the IRES. Thus, our results support rpS5 as the critical element in positioning the HCV RNA on the 40 S ribosomal subunit during translation initiation.