Oxygen mass transfer and scale-up studies in baffled roller bioreactors.

Oxygen mass transfer was studied in conventional, bead mill and baffled roller bioreactors. Using central composite rotational design, impacts of size, rotation speed and working volume on the oxygen mass transfer were evaluated. Baffled roller bioreactor outperformed its conventional and bead mill counterparts, with the highest k(L)a obtained in these configurations being 0.58, 0.19, 0.41 min(-1), respectively. Performances of the bead mill and baffled roller bioreactor were only comparable when a high bead loading (40%) was applied. Regardless of configuration increase in rotation speed and decrease in working volume improved the oxygen mass transfer rate. Increase in size led to enhanced mass transfer and higher k(L)a in baffled roller bioreactor (0.49 min(-1) for 2.2 L and 1.31 min(-1) for 55 L bioreactors). Finally, the experimentally determined k(L)a in the baffled roller bioreactors of different sizes fit reasonably well to an empirical correlation describing the k(L)a in terms of dimensionless numbers.

Oxidation of phenol in a bioremediation medium using Fenton's reagent.

The oxidation of phenol by Fenton's reagent was investigated in a medium suitable for bioremediation. An experimental design approach, based on a central composite rotatable design, was used to quantify the effects of H2O2 concentration (2000 to 5000 mg 1(-1)) and FeSO4.7H2O concentration (500 to 2000 mg 1(-1)). Performance of the chemical oxidation by Fenton's reagent was evaluated by determining the percentage of phenol oxidized at equilibrium. The analysis of variance test indicated that both H2O2 and FeSO4.7H2O concentrations had a positive effect on phenol oxidation. Hydrogen peroxide concentration was the dominating parameter for the removal of phenol by Fenton's reagent. The optimal concentrations of H2O2 and FeSO4.7H2O for complete oxidation of 2000 mg 1(-1) phenol in the medium were found to be 4340 mg 1(-1) and 1616 mg 1(-1), respectively, at 25 degrees C and pH 3. Oxidation of phenol in the culture medium was found to be significantly different than in pure water.

Batch and continuous biooxidation of sulphide by Thiomicrospira sp. CVO: reaction kinetics and stoichiometry.

Aqueous phase biooxidation of sulphide by the novel sulphide-oxidizing bacterium Thiomicrospira sp. CVO was studied in batch and continuous systems. CVO was able to oxidize sulphide at concentrations as high as 19 mM. Sulphide biooxidation occurred in two distinct phases, one resulting in the formation of sulphur and possibly other dissolved sulphur compounds rather than sulphate, followed by sulphate formation. The specific growth rate of CVO in the first and second phases were 0.17-0.27 and 0.04-0.05 h(-1), respectively. Nitrite accumulated in the culture during the first phase and was consumed during the second phase. The composition of end-products was influenced by the ratio of sulphide to nitrate initial concentrations. At a ratio of 0.28, sulphate represented 93% of the reaction products, while with a ratio of 1.6 the conversion of sulphide to sulphate was only 9.3%. In the continuous bioreactor, complete removal of sulphide was observed at sulphide volumetric loading rates as high as 1.6mM/h (residence time of 10h). Overall sulphide removal efficiency decreased continuously upon further increases in volumetric loading rate. However, the volumetric removal rate increased until a maximum value of 2.4mM/h was obtained at a loading rate of 3.2mM/h. The corresponding sulphide conversion and residence time were 76% and 5.6h, respectively. As expected from the high ratio of sulphide to nitrate loading rates (1.7-1.9 mM/h), no sulphate was formed in the continuous reactor. Using the experimental data the value of maximum specific growth rate, saturation constant, decay coefficient, maintenance coefficient and yield were determined to be 0.36 h(-1), 1.99 mM sulphide, 0.0014 h(-1), 0.078 mmol sulphide/mg ATPh and 0.018 mg ATP/mmol sulphide, respectively.

Male partner screening before in vitro fertilization: preselecting patients who require intracytoplasmic sperm injection with the sperm penetration assay.

OBJECTIVES: To determine the diagnostic accuracy of the sperm penetration assay (SPA) and standard semen parameters for subsequent fertilization in in vitro fertilization-embryo transfer (IVF-ET). DESIGN: Prospective study. SETTING: Andrology Laboratory, and university research laboratory. PATIENTS: Two hundred sixteen couples undergoing male-partner screening before IVF-ET (265 cycles). INTERVENTION(S): Male-partner screening (semen analyses [SA] and SPA), standard IVF-ET procedures, follow-up of fertilization in IVF-ET. MAIN OUTCOME MEASURE(S): Diagnostic accuracy of SA and SPA for prediction of fertilization in IVF-ET. RESULT(S): The SPA predicted IVF fertilization with high negative (84%) and positive (98%) predictive rates, and correct prediction in 88% of cycles. In contrast, sperm concentration, motility, morphology, and complete SA showed poor diagnostic accuracy, with correct prediction of IVF fertilization in 64%, 65%, 45%, and 68% of cycles, respectively. CONCLUSION(S): Very low sperm concentration and/or motility were good predictors of poor IVF fertilization, however, low to normal semen parameters were not predictive of successful IVF fertilization. The SPA is a useful screening tool that predicts IVF fertilization with high diagnostic accuracy. The SPA may be useful to discriminate between those couples with a high probability of normal fertilization in IVF and those with a low probability of normal fertilization that may benefit from assisted fertilization by intracytoplasmic sperm injection (ICSI).

How to be paid for what you do: know the process.

Current Procedural Terminology and ICD-9-CM codes are tools used in clinical medicine to define work done and diagnoses or conditions for which the work was performed. It is important that all physicians become knowledgeable about these schemes to describe services provided correctly and accurately.

Modelling plasmid instability in batch and continuous fermentors.

The probability of complete loss of plasmid material from plasmid bearing cells undergoing active growth has been modelled and incorporated into predictions for the dynamic concentrations of plasmid bearing cells in both batch and continuous flow, stirred tank bioreactors. The new model is based on an extension of the well-used model of Imanaka and Aiba [Ann. New York Acad. Sci. 369 (1981) 1] and is relatively easy to use compared to complex structured models. The new model predicts that both accelerating and decelerating rates of plasmid loss occur in both batch and continuous flow operation, and agrees well with data collected here and published earlier by others.

Recurrent instability of the elbow in the Ehlers-Danlos syndrome. A report of three cases and a new technique of surgical stabilisation.

We present three cases of recurrent instability of the elbow in association with the Ehlers-Danlos syndrome. The pattern of instability has not previously been reported. We describe our procedure for achieving stability using a bone graft to the olecranon fossa which gave a functional range of movement.

Femoral nailing for metastatic disease of the femur: a comparison of reamed and unreamed femoral nailing.

A total of 73 consecutive intramedullary femoral nails were inserted for metastatic disease of the femur; 43 were reamed and 30 were solid nails. The two groups were similar with regards to age, type of primary tumour, anatomical site, acute or 'impending' fracture and postoperative survival. The 'solid' nail offers a satisfactory alternative form of stabilisation for metastatic disease of the femur with rates of implant failure which are comparable with the reamed nail. In this series bilateral nailing was not associated with any increase in mortality. Contrary to other reports, imposing a delay in patients with pain and a short life expectancy seems unjustified. The use of the 'solid' femoral nail does not prevent sudden death due to massive fat embolism.

Quantitative and qualitative analysis of type III antifreeze protein structure and function.

Some cold water marine fishes avoid cellular damage because of freezing by expressing antifreeze proteins (AFPs) that bind to ice and inhibit its growth; one such protein is the globular type III AFP from eel pout. Despite several studies, the mechanism of ice binding remains unclear because of the difficulty in modeling the AFP-ice interaction. To further explore the mechanism, we have determined the x-ray crystallographic structure of 10 type III AFP mutants and combined that information with 7 previously determined structures to mainly analyze specific AFP-ice interactions such as hydrogen bonds. Quantitative assessment of binding was performed using a neural network with properties of the structure as input and predicted antifreeze activity as output. Using the cross-validation method, a correlation coefficient of 0.60 was obtained between measured and predicted activity, indicating successful learning and good predictive power. A large loss in the predictive power of the neural network occurred after properties related to the hydrophobic surface were left out, suggesting that van der Waal's interactions make a significant contribution to ice binding. By combining the analysis of the neural network with antifreeze activity and x-ray crystallographic structures of the mutants, we extend the existing ice-binding model to a two-step process: 1) probing of the surface for the correct ice-binding plane by hydrogen-bonding side chains and 2) attractive van der Waal's interactions between the other residues of the ice-binding surface and the ice, which increases the strength of the protein-ice interaction.

Critical mandates: prevention and health promotion.

Health maintenance organizations are supposed to maintain health, not just contain the cost of treating illness. Prevention and health promotion are critical mandates for managed care organizations, including managed behavioral health plans. More often than not, however, health plans have neglected to include prevention and behavioral health promotion services within their spectrum of covered benefits. In this article, the authors explain why there is a growing trend toward including coverage for prevention and promotion services in managed behavioral health plans, including the financial advantages and cost-containment opportunities that result. The article also illustrates several simple and straightforward models for structuring prevention benefits, managing the utilization and quality of prevention services, and including community-based preventive services organizations in provider networks.

Permanent impairment of embryo development by hydrosalpinges.

Recent reports suggest a deleterious effect of hydrosalpinges on pregnancy outcome for in-vitro fertilization (IVF) and improvement following surgical treatment. We compared the effect of hydrosalpinx on pregnancy outcome in 286 patients having 348 IVF cycles and followed the development of untransferred embryos for 7 days to determine if hydrosalpinges affect oocyte quality or embryo development. The delivery rate per retrieval was significantly lower for patients with hydrosalpinx, but was restored by surgical treatment to that of patients without hydrosalpinx. However, the implantation rate per embryo transferred and normal blastulation of untransferred embryos, which were significantly decreased in patients with hydrosalpinx, and growth arrest and degeneration of untransferred embryos, which were significantly increased compared to patients without hydrosalpinx, were not restored by surgical treatment of hydrosalpinges. We conclude that surgical treatment of hydrosalpinges decreases early pregnancy loss and improves pregnancy outcome, possibly by diminishing reversible deleterious effects exerted on the endometrium. As we have seen in our laboratory, hydrosalpinges may have a permanent negative influence on ovarian function, follicular development and oocyte quality since implantation of transferred embryos and normal blastulation of untransferred embryos remain low, and in-vitro growth arrest and degeneration remain high despite surgical treatment of hydrosalpinges.

Survey results on behavioral health promotion in managed primary health care.

Casual observation suggests that many managed health care providers support health promotion and preventive care, including efforts addressing such behavioral health objectives as reduced alcohol use during pregnancy, prevention of family violence, and improved parenting. Respondents from roughly 40 percent of 200 health maintenance organizations (HMOs) selected for a 1995-1996 survey reported some type of health promotion activities with potential behavioral health impact. These 80 HMOs were found to be divided among eight distinct models of interaction between behavioral health promotion and managed primary health care.

Assessment of methodological practices in the evaluation of alcohol and other drug (AOD) abuse prevention.

No authoritative consensus has been achieved on which substance abuse prevention activities are effective for given populations. One response to concern about "what works" took the form of a National Structured Evaluation (NSE), mandated by the Anti-Drug Abuse Act of 1988. The present paper describes the NSE's pivotal task of determining whether evaluation methodologies applied to substance abuse prevention were adequate to produce credible findings. The lessons learned from this evaluation experience, in turn, offer guidance on changes that must be made in the application of evaluation methodology prior to a conclusive demonstration of the value of prevention efforts.

Cometabolic degradation of 4-chlorophenol by Alcaligenes eutrophus.

Alcaligenes eutrophus was grown in batch cultures using either phenol as a sole substrate or mixtures of phenol and 4-chlorophenol. Phenol was found to be the sole source for carbon and energy while 4-chlorophenol was utilized only as a cometabolite. Maximum growth rates on phenol reached only 0.26 h-1, significantly below the growth rates reported earlier with Pseudomonas putida. The cometabolite was found to decrease biomass yield and increase lag time before logarithmic growth occurred. Both phenol and 4-chlorophenol were found to inhibit the growth rate linearly with maximum concentrations of 1080 ppm and 69 ppm respectively, beyond which no growth occurred. The best-fit parameters are incorporated into a simple, dynamic (i.e. time-varying) model capable of predicting all the batch growth conditions presented here. It is shown that P. putida is capable of faster bioremediation when phenol is the sole carbon source or for mixed substrates with low concentrations of the cometabolite, but for high concentrations of 4-chlorophenol, A. eutrophus becomes superior because of the long lag times that occur in the Pseudomonas species.

Autologous granulosa cell coculture demonstrates zygote suppression of granulosa cell steroidogenesis.

OBJECTIVE: To determine if embryos can modulate steroid hormone production by luteinized granulosa cells. DESIGN: Granulosa cells obtained from follicular aspirates were cultured alone or in the presence of a two-pronuclear zygote. The production of E2 and P by these cultures was evaluated by RIA. SETTING: In Vitro Fertilization Unit in an academic research environment. PATIENTS: Sixteen women undergoing IVF. INTERVENTIONS: Standard IVF-ET treatment cycle using leuprolide acetate for pituitary desensitization before hMG or urofollitropin for ovarian stimulation. MAIN OUTCOME MEASURES: Estradiol and P concentration in culture media of luteinized granulosa cells alone or granulosa cells cocultured with a two-pronuclear embryo. RESULTS: Both E2 and P production by luteinized granulosa cells was reduced when cultured in the presence of an embryo. CONCLUSIONS: Human embryos secrete a factor that regulates granulosa cell steroidogenesis.

Granulosa cell co-culture enhances human embryo development and pregnancy rate following in-vitro fertilization.

A preliminary study and related clinical trial were performed to evaluate the effects of granulosa-lutein cell co-culture on human embryo development and pregnancy rates for in-vitro fertilization (IVF). In the study, sibling two-pronuclear zygotes were randomly allocated to culture with (co-culture) or without (control) autologous granulosa-lutein cells. After 24 h, embryos were examined for blastomere number and degree of fragmentation. Co-culture had no effect on the average number of blastomeres per embryo at 24 h; however, fragmentation was significantly decreased in co-cultured embryos (0.7 +/- 0.1) compared with controls (1.3 +/- 0.2; P < 0.05). In the subsequent clinical trial, all two-pronuclear zygotes were co-cultured for 48 h prior to embryo transfer. The live birth rate per embryo transfer was 43.4% with an implantation rate per embryo of 17.6%. Of the untransferred embryos, 68% developed to the blastocyst stage and were cryopreserved. We conclude that the simple system of autologous granulosa-lutein cell co-culture improves embryo development, implantation and subsequent pregnancy rates for IVF.