Biomedical subjects

M Lane

Publications and source records attributed to M Lane.

At least 19 recordsLinked to original sources

PubMed2007

A comparison of hypnotic and analgesic based sedation in a general intensive care unit.

BACKGROUND: Sedation of the critically ill patient has several components including hypnosis and analgesia. Hypnotic-based sedation (HBS), where midazolam and/or propofol are used, with morphine or another analgesic added as needed has been common. The advent of remifentanil has allowed greater use of analgesia-based sedation (ABS) where relief of discomfort from the tracheal tube or pain are the important objectives, and hypnosis is given as necessary. Method. We compared HBS and ABS (remifentanil-based sedation) within a general intensive care unit (ICU). During the first study period of 12 weeks, 111 patients received HBS. After the development of new guidelines for the use of remifentanil in the ICU, a second 12 week study period used an analgesia-based regimen, with hypnotics added only if needed. RESULTS: Ninety-six patients received ABS, and 79 received remifentanil. It was possible to manage 29 (37%) of the patients receiving remifentanil without the use of supplementary hypnotic agents. In the remaining 63% the use of remifentanil was associated with a reduction in the amount and duration of propofol used. Significantly more patients receiving ABS had satisfactory levels of sedation during synchronized intermittent mandatory ventilation (19 [2,55] vs 50 [14,83], P<0.001). CONCLUSIONS: The use of ABS allowed patients to be managed more comfortably, either without a hypnotic drug or with less hypnotic drug, than using conventional HBS.

Adolescent↗

PubMed2006

Efficacy of particle-based DNA delivery for vaccination of sheep against FMDV.

As an alternative strategy to classical inactivated viral vaccine against FMDV, naked DNA vaccine is attractive because of safety, flexibility and low cost. However DNA vaccination is usually poorly efficient in target species. Indeed we found that naked DNA plasmids encoding for P1-2A3C3D and GM-CSF proteins did not induce any detectable immunity against FMDV in sheep. Interestingly, we demonstrate herein that formulations of DNA on poly(D,L-lactide-co-glycolide) (PLG) or in lipofectin triggered divergent types of immune responses: PLG stimulated a T cell response and could elicit significant neutralising antibody titers, whereas lipofectin generated even higher antibody titers but no significant T cell response. The DNA/PLG regimen used in five sheep protected against clinical symptoms and viraemia and prevented the carrier state in four of them. Thus formulated DNA can be remarkably efficient against FMDV in a ruminant species that is usually refractory to DNA vaccination.

Animals↗

PubMed2006

Mathematical modelling of oxygen concentration in bovine and murine cumulus-oocyte complexes.

Immature oocytes benefit from nutrient modification of the follicular environment by the surrounding cumulus mass. However, the oxygen concentration that the oocyte may be exposed to could be lower than the antral follicular concentration due to the metabolism of surrounding cumulus cells. Using metabolic data previously determined, we have developed a mathematical model of O(2) diffusion across the bovine and murine cumulus-oocyte complex. From this we have determined that across a physiological range of external pO(2), less than 0.25% and 0.5% O(2) is removed by cumulus cells within the bovine and murine cumulus-oocyte complex respectively. Our model differs from others as it: incorporates a term that allows for nonlinear variation of the oxygen consumption rate with oxygen concentration; considers two regions (oocyte and cumulus) sharing a common boundary, both of which consume oxygen at different non linear rates. Cumulus cells therefore remove little O(2), thus sparing this essential gas for the oocyte, which is dependent on ATP generation via oxidative phosphorylation.

Animals↗

PubMed2004

Matched study of three methods for palliation of malignant pyloroduodenal obstruction.

BACKGROUND: The traditional management of pyloroduodenal obstruction is open gastrojejunostomy (OGJ). More recently laparoscopic gastrojejunostomy (LGJ) and endoscopic stenting (ES) have been introduced. The aim of this study was to evaluate the three approaches to the palliation of malignant pyloroduodenal obstruction. METHODS: All patients who underwent surgery (open and laparoscopic) for malignant pyloroduodenal obstruction at Auckland City Hospital between 1989 and 2002 inclusive were identified from International Classification of Diseases (ICD) 10 codes and from the Otago Surgical Audit Database. Patients who had an endoscopic stent were identified from the Endoscribe database. A review of medical records was conducted and data recorded in a structured pro forma. There were 181 patients with malignant pyloroduodenal obstruction of whom 56 patients had OGJ, 14 had LGJ and 16 had ES. Patients in the LGJ and ES groups were matched with those who underwent OGJ with respect to American Society of Anesthesiologists (ASA) grade (I-V), age (within 10 years) and level of obstruction (pylorus, first part of duodenum D1, D2, D3 and D4). The primary outcomes compared between the groups were time to starting free oral fluids and light diet, length of stay and survival. RESULTS: There were no significant differences in age, sex, ASA grade and level of obstruction between the matched OGJ (n=16), LGJ (n=14) and ES (n=16) groups. There was a significant reduction in time to starting free oral fluids and light diet, and length of stay after the procedure, in the ES group. Patients who underwent surgical palliation of the obstruction had significantly more complications than those who underwent stenting (P=0.016). There were no significant differences in requirement for biliary drainage either before or after the procedure between the three groups. Survival was shortest in the ES group. CONCLUSION: This matched study showed significant advantages for ES compared with OGJ and LGJ in the palliation of malignant pyloroduodenal obstruction.

Adult↗

PubMed2004

The growth profile, thermotolerance and biofilm formation of Enterobacter sakazakii grown in infant formula milk.

AIMS: To study the growth, thermotolerance and biofilm formation of the emergent pathogen Enterobacter sakazakii in infant formula milk (IFM). METHODS AND RESULTS: The temperature range, death kinetics and biofilm formation of E. sakazakii were determined using impedance microbiology and conventional methods. In IFM the organism grew as low as 6 degrees C and optimally at 37-43 degrees C. In faecal coliform tests, 23% of strains (n = 70) produced gas from lauryl sulphate broth (LSB) at 44 degrees C after 48 h incubation. Three strains failed to grow in LSB at any of the temperatures. The D-value of cells suspended in IFM was determined between 54 and 62 degrees C. The resultant z-value was 5.7 degrees C. The organism was able to adhere and grow on latex, polycarbonate, silicon and to a lesser extent stainless steel. CONCLUSIONS: Enterobacter sakazakii was able to grow at refrigeration temperatures and on infant-feeding equipment. The thermotolerance of the organism was similar to other Enterobacteriaceae and should be killed during standard pasteurization treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: Enterobacter sakazakii has been associated with infant meningitis through consumption of contaminated IFM. Enterobacter sakazakii is able to grow in IFM during storage at refrigeration temperatures and attach to infant-feeding equipment, which may become reservoirs of infection.

Animals↗

PubMed2003

Recombinant human albumin supports hamster in-vitro fertilization.

BACKGROUND: Serum albumin is normally required to support sperm capacitation and IVF, but its mechanism of action is not well understood. Commercial serum albumin preparations are contaminated with a variety of other proteins and compounds, and their biological activity is variable. Recombinant human albumin (rHA) might replace serum albumin for IVF. METHODS: rHA was examined for its ability to capacitate hamster spermatozoa and to support fertilization in vitro. A standardized hamster IVF system was used to compare the capacitation-supporting activities of rHA and two commercial preparations of bovine serum albumin (BSA) in a chemically defined culture medium. Epididymal spermatozoa were incubated for 4 h at 37 degrees C under 5% CO(2) in air in either the basic medium containing rHA, one of the two BSA preparations or no protein, and then cultured in the same medium with ovulated oocytes for another 4 h. The experiment was replicated five times. RESULTS: Spermatozoa incubated in protein-free medium fertilized only one oocyte (2% of total), significantly less than any of the other three treatment conditions (P < 0.01); spermatozoa incubated in medium containing rHA or BSA fertilized 86-93% of oocytes. There were no differences between the three albumin-containing treatment groups. CONCLUSION: rHA is equivalent to commercial serum albumin preparations in its ability to support sperm capacitation and fertilization in this test system. This finding has considerable practical implications for human IVF and may also help efforts to elucidate the mechanism of sperm capacitation.

Animals↗

PubMed2002

Serum pharmacokinetics and tissue and milk residues of oxytetracycline in goats following a single intramuscular injection of a long-acting preparation and milk residues following a single subcutaneous injection.

Separate groups of goats were used to determine drug depletion patterns in serum (n=10), tissue (n=20) and milk (n=8) following a single intramuscular (i.m.) dose of 20 mg/kg of a long-acting oxytetracycline (OTC) formulation (Liquamycin LA-200). Milk residues were also determined following a subcutaneous (s.c.) administration of the same product at the same dose. Serum samples were taken for 24 h post-treatment and tissues (fat, liver, kidney, muscle and injection site) collected at 4, 7, 14, 21 and 28 days following injection. Milk from lactating goats was collected every 12 h for 8 days following both the i.m. and s.c. treatments utilizing an intervening 5-week washout period. Residues in serum and tissue were measured using a microbial inhibition assay, while milk residues were measured using both a microbial inhibition assay and a validated HPLC method. The serum pharmacokinetic parameters of OTC in goats were determined, with a mean AUC=67.4 microg h/mL, mean terminal half-life=14.4 h, and apparent clearance=0.33 L/kg h. Tissue half-lives could not be determined with confidence because the collection times provided only two points at which residues could be measured for most tissues. Oxytetracycline residues in all goat tissue samples measured less then cattle tissue tolerance by 96 h postdosing. One-compartment model describing milk depletion data for i.m. and s.c. dosing had terminal slope half-lives of 20.1 and 36.1 h, respectively. By 96 h post-treatment none of the milk samples contained OTC residues in excess of the cattle milk tolerance (0.3 p.p.m.). For both milk and tissue, the upper-bound 99% confidence intervals for the samples taken from goats 96 h postdosing were lower than approved cow milk and tissue tolerances.

Animals↗

PubMed2001

The in-vitro porcine adhesion model is not predictive of the esophageal transit of risedronate tablets in humans.

Mucosal damage due to esophageal adhesion of pharmaceuticals is a continued concern to both health care providers and drug manufacturers. As a result of this concern, dosage forms are now being designed to exhibit minimal esophageal adhesion. Previous researchers have used an in-vitro porcine esophageal model to determine the propensity for formulations to adhere to the esophagus as an alternative to human scintigraphy studies. This study used a porcine esophageal adhesion model similar to that used previously to determine the adhesiveness of placebo bisphosphonate formulations. Results are analogous to those obtained by previous researchers, with film-coated tablets showing greater adhesiveness than uncoated tablets. These same tablet formulations were also evaluated previously by a human scintigraphy study, and the results were exactly opposite of those obtained using the in-vitro porcine model. In the human scintigraphy study, the film-coated placebo risedronate tablet had a faster transit time than an uncoated round placebo tablet. In conclusion, the in-vitro porcine esophageal model is not predictive of esophageal transit in man and gamma scintigraphy is the preferred method to evaluate esophageal transit.

Animals↗

PubMed2001

A cross-link breaker has sustained effects on arterial and ventricular properties in older rhesus monkeys.

Nonenzymatic glycosylation and cross-linking of proteins by glucose contributes to an age-associated increase in vascular and myocardial stiffness. Some recently sythesized thiazolium compounds selectively break these protein cross-links, reducing collagen stiffness. We investigated the effects of 3-phenacyl-4,5-dimethylthiazolium chloride (ALT-711) on arterial and left ventricular (LV) properties and their coupling in old, healthy, nondiabetic Macaca mulatta primates (age 21 +/- 3.6 years). Serial measurements of arterial stiffness indices [i.e., aortic pulse wave velocity (PWV) and augmentation (AGI) of carotid arterial pressure waveform] as well as echocardiographic determinations of LV structure and function were made before and for 39 weeks after 11 intramuscular injections of ALT-711 at 1.0 mg/kg body weight every other day. Heart rate, brachial blood pressure, and body weight were unchanged by the drug. PWV and AGI decreased to a nadir at 6 weeks [PWV to 74.2 +/- 4.4% of baseline (B), P = 0.007; AGI to 41 +/- 7.3% of B, P = 0.046], and thereafter gradually returned to baseline. Concomitant increases in LV end diastolic diameter to 116.7 +/- 2.7% of B, P = 0.02; stroke volume index (SV(index)) to 173.1 +/- 40.1% of B, P = 0.01; and systolic fractional shortening to 180 +/- 29.7% of B, P = 0.01 occurred after drug treatment. The LV end systolic pressure/SV(index), an estimate of total LV vascular load, decreased to 60 +/- 12.1% of B (P = 0.02). The LV end systolic diameter/SV(index), an estimate of arterio-ventricular coupling, was improved (decreased to 54.3 +/- 11% of B, P < 0.002). Thus, in healthy older primates without diabetes, ALT-711 improved both arterial and ventricular function and optimized ventriculo-vascular coupling. This previously unidentified cross-link breaker may be an effective pharmacological therapy to improve impaired cardiovascular function that occurs in the context of heart failure associated with aging, diabetes, or hypertension, conditions in which arterial and ventricular stiffness are increased.

Aging↗

PubMed2001

Mechanisms for managing cellular and homeostatic stress in vitro.

The ability to maintain embryo development in culture depends upon the ability of the embryo to maintain cellular homeostasis. Disruptions in the ability to regulate cellular homeostasis such as pH, calcium levels and osmotic pressure result in perturbed development and a reduced ability to establish and maintain a pregnancy following transfer. Therefore, it is important that in vitro conditions are designed to minimize stress on the embryo and maximize the ability of the embryo to maintain cellular homeostasis. While embryos do exhibit a degree of plasticity and can adapt to their environment, this requires expenditures of extra energy which negatively impacts viability. Therefore, reducing stress by taking into account the physiology of the embryo is essential for the maintenance of developmental competence in vitro.

Animals↗

PubMed2001

Substrate utilization in porcine embryos cultured in NCSU23 and G1.2/G2.2 sequential culture media.

Embryo metabolism is an indicator of viability and, therefore, efficiency of the culture medium. Currently, little is known regarding porcine embryo metabolism. The objective of our study was to evaluate glucose and pyruvate uptake and lactate production in porcine embryos cultured in two different media systems. Oocytes were matured and fertilized according to standard protocols. Embryos were allocated randomly into two culture treatments, NCSU23 medium or G1.2/G2.2 sequential culture media 6-8 h post-insemination (hpi). Embryo substrate utilization was measured at the two-cell (24-30 hpi), 8-cell (80 hpi), morula (120 hpi), and blastocyst (144 hpi) stages using ultramicrofluorimetry. Glucose uptake was higher (P < 0.05) in two-cell embryos cultured in G1.2 than in NCSU23 medium (4.54 +/- 0.71, 2.16 +/- 0.87 pmol/embryo/h, respectively). Embryos cultured in G1.2/G2.2 produced significantly more lactate than those in NCSU23 at the eight-cell stage (9.41 +/- 0.71, 4.42 +/- 0.95 pmol/embryo/hr, respectively) as well as the morula stage (11.03 +/- 2.31, 6.29 +/- 0.77 pmol/embryo/hr, respectively). Pyruvate uptake was higher (P < 0.05) in morula cultured in G1.2/G2.2 versus NCSU23 (22.59 +/- 3.92, 11.29 +/- 1.57 pmol/embryo/h, respectively). Lactate production was greater (P < 0.05) in blastocysts cultured in G1.2/G2.2 (38.13 +/- 15.94 pmol/embryo/h) than blastocysts cultured in NCSU23 (8.46 +/- 2.38 pmol/embryo/h). Pyruvate uptake was also greater in blastocysts cultured in G1.2/G2.2 (24.3 +/- 11.04) than those in NCSU23 (11.30 +/- 2.70). When cultured in NCSU23 medium, two- and eight-cell embryos utilized less glucose than morulae and blastocysts, and two-cell embryos produced less lactate than blastocysts (P < 0.05). In G1.2/G2.2 media, two-cells took up less pyruvate than morulae or blastocysts, while blastocysts produced more lactate and utilized more glucose than two-cell, eight-cell and morula stage embryos (P < 0.05). As in other species, glycolysis appears to be the primary metabolic pathway in post-compaction stage porcine embryos. Culture medium composition affects not only substrate uptake, but also metabolic pathways by which these substrates are utilized in porcine embryos at several developmental stages.

Animals↗

PubMed2001

Vitrification of mouse oocytes using a nylon loop.

Cryopreservation of mouse oocytes was improved by the use of ultra-rapid vitrification using a nylon loop of 0.5 mm diameter. Oocytes that were vitrified using the loop survived at high rates and were fertilized following a small hole being made in the zona pellucida (69.8%) and developed to the blastocyst stage in culture (67.4%) at similar rates to that of oocytes that were not cryopreserved. Blastocysts resulting from oocytes vitrified using the nylon loop had similar development of the inner cell mass and trophectoderm as blastocysts from non-cryopreserved oocytes. In contrast, oocytes that were cryopreserved using a slow-freezing protocol where most of the Na+ is replaced with choline had lower rates of fertilization (39.5%), reduced development to the blastocyst stage (25.7%), and blastocysts had reduced development of the inner cell mass. Blastocysts derived from oocytes that were vitrified with the nylon loop were able to implant (88.0%) and develop into fetuses (56.5%) at significantly higher rates compared to blastocysts derived from oocytes that were slow-frozen (52.4 and 26.2%, respectively). Vitrification of mouse oocytes using the nylon loop results in the retention of viability of the oocytes and subsequent embryos.

Animals↗

PubMed2001

Assessment of metabolism of equine morulae and blastocysts.

Nutrient uptakes and metabolite production by equine morula and blastocyst stage embryos were determined by non-invasive microfluorometry. Equine morula took up equal amounts of both pyruvate and glucose. However, at the early blastocyst there was a small increase in glucose uptake and, by the expanded blastocyst stage, glucose was the predominant nutrient. Expanded blastocysts took up five times more glucose than pyruvate. Expanded blastocysts exhibited an exponential increase in glucose uptake and lactate production with respect to both diameter and surface area. As less than 50% of the glucose was accounted for by lactate production, the equine blastocyst appears to have a significant capacity to oxidize glucose. Embryos with a higher morphological grade consumed more nutrients than those with a poorer morphology. However, there was a large range in nutrient consumption within the highest grade blastocysts. This suggests that nutrient uptake may be useful as a viability marker of equine blastocysts.

Animals↗

PubMed2001

Inhibiting 3-phosphoglycerate kinase by EDTA stimulates the development of the cleavage stage mouse embryo.

Addition of EDTA to the medium significantly enhances mouse embryo development in culture. Embryos cultured in the absence of EDTA exhibit abnormal increases in glycolytic activity that result in reduced development. Culture with EDTA was able to prevent this increase in glycolysis and, therefore, maintain developmental competence. EDTA was shown to inhibit the activity of the glycolytic enzyme, 3-phosphoglycerate kinase. Additionally, the effect of EDTA on maintaining high rates of embryo development in culture could be mimicked by the addition of Cibacron blue, an inhibitor of 3-phosphoglycerate kinase. The inhibition of 3-phosphoglycerate kinase by EDTA could be overcome by the addition of exogenous magnesium, indicating that the effect of EDTA was to reduce the availability of this co-factor to the glycolytic kinases. Embryos cultured with EDTA had significantly lower levels of intracellular magnesium compared to embryos cultured without EDTA. Therefore, the effect of EDTA appears to be as a chelator of divalent cations such as magnesium, that are required for normal activity of kinases such as 3-phosphoglycerate kinase.

Animals↗

PubMed2001

Comparison of postoperative outcomes in ulcerative colitis and familial polyposis patients after ileoanal pouch operations.

BACKGROUND: Pouchitis is a poorly understood inflammatory condition that occurs in the ileal pouches of patients who have undergone the ileal-pouch anal anastomosis after restorative proctocolectomy. This postoperative condition is much more common in patients with ulcerative colitis (UC) than familial adenomatous polyposis (FAP) colitis. It has been suggested that, owing to pouchitis, UC patients do not attain the same quality of life that FAP patients do after the ileal-pouch anal anastomosis operation. We hypothesized that health-related quality of life does not differ between FAP and UC patients. METHODS: We analyzed the postoperative morbidity and gastrointestinal function in 110 consecutive patients having undergone the ileal-pouch anal anastomosis for either UC or FAP at OU Medical Center from 1983 to 2000 by retrospective record review. Health-related quality of life was assessed in 83 patients using the Short Inflammatory Bowel Disease Questionnaire (SIBDQ) and the Medical Outcome Study Short-Form 36 (SF-36) questionnaire. RESULTS: With the exception of pouchitis, there was no difference in perioperative outcome, morbidity, or functional status between UC and FAP patients. The SIBDQ and SF-36 revealed no statistically significant difference between FAP and UC patients. CONCLUSIONS: As expected, UC patients are more likely to develop pouchitis. Despite this, our data reveal that both patient groups enjoy a similarly good functional status and quality of life.

Adenomatous Polyposis Coli↗

PubMed2001

Noninvasive assessment of human embryo nutrient consumption as a measure of developmental potential.

OBJECTIVE: To determine the relationship between blastocyst development and morphology and embryo metabolism. DESIGN: Noninvasive assessment of carbohydrate uptake and ammonium production by individual embryos. SETTING: Private assisted reproductive technology unit. PATIENT(S): Patients donated, with consent, cryopreserved pronucleate embryos and noncryopreserved blastocysts. INTERVENTION(S): Culture of 60 thawed pronucleate embryos in sequential media to the blastocyst stage with concomitant noninvasive analysis of embryo metabolism and analysis of 13 blastocysts from noncryopreserved embryos. MAIN OUTCOME MEASURE(S): Pyruvate and glucose consumption as well as blastocyst formation and quality. RESULT(S): Pyruvate and glucose uptakes on day 4 were significantly higher by embryos that went on to form blastocysts than by embryos that failed to develop to the blastocyst stage. Glucose uptakes were greatest in those blastocysts of highest grade, whereas pyruvate uptakes were similar irrespective of blastocyst grade, indicating that glucose is the more important nutrient for the human blastocyst. Among blastocysts of the same grade from the same patient, there was considerable spread of glucose consumption, indicating that glucose consumption may be of use in identifying blastocysts for transfer. Ammonium production by individual embryos was also measured, reflecting amino acid transamination and use by the human embryo. CONCLUSION(S): The ability to identify in culture the embryo with the highest developmental potential will facilitate the move to single-embryo transfers.

Blastocyst↗

PubMed2001

Effect of essential amino acids on mouse embryo viability and ammonium production.

PURPOSE: To examine the effect of essential amino acids concentrations on mouse embryo development. METHODS: Mouse embryos were cultured in medium with different concentrations of essential amino acids and development to the blastocyst stage and viability assessed. Ammonium production resulting from medium breakdown and amino acid metabolism by embryos were also assessed. RESULTS: Reducing the essential amino acid concentration significantly increased blastocyst development and cell numbers. Lowering the essential amino acid concentration decreased ammonium production in the medium. CONCLUSIONS: Culture media for the development of preimplantation embryos should have a reduced essential amino acid concentration to facilitate embryo development.

Amino Acids, Essential↗

PubMed2001

Iodoacetate protects hippocampal neurons against excitotoxic and oxidative injury: involvement of heat-shock proteins and Bcl-2.

Mild metabolic stress may increase resistance of neurons in the brain to subsequent, more severe insults, as demonstrated by the ability of ischemic pre-conditioning and dietary restriction to protect neurons in experimental models of stroke- and age-related neurodegenerative disorders. In the present study we employed iodoacetic acid (IAA), an inhibitor of glyceraldehyde-3-phosphate dehydrogenase, to test the hypothesis that inhibition of glycolysis can protect neurons. Pre-treatment of cultured hippocampal neurons with IAA can protect them against cell death induced by glutamate, iron and trophic factor withdrawal. Surprisingly, protection occurred with concentrations of IAA (2-200 nM) much lower than those required to inhibit glycolysis. Pre-treatment with IAA results in suppression of oxyradical production and stabilization of mitochondrial function in neurons after exposure to oxidative insults. Levels of the stress heat-shock proteins HSP70 and HSP90, and of the anti-apoptotic protein Bcl-2, were increased in neurons exposed to IAA. Our data demonstrate that IAA can stimulate cytoprotective mechanisms within neurons, and suggest the possible use of IAA and related compounds in the prevention and/or treatment of neurodegenerative conditions.

Adenosine Triphosphate↗