Conventional surgery in colon cancer with comparison to complete mesocolic excision and central vascular ligation: initial experience in a tertiary centre.

INTRODUCTION: The complete mesocolic excision (CME) and central vascular ligation (CVL) is an advanced surgical technique used to treat colon cancer. It combines the removal of the affected portion of the colon and surrounding lymph nodes with an improved method of controlling the vascular supply to the tumour. MATERIALS AND METHODS: A retrospective study of patients with colon cancer underwent right hemicolectomy (either CME and CVL or conventional method) were operated by colorectal surgeons in a tertiary centre in Kuala Lumpur from 2018 to 2020. We review the data to compare the oncological, pathological and surgical outcomes of both techniques. Categorical variables were presented as frequencies and percentages. Continuous variables were compared using an independent t-test or Mann-Whitney Rank U test. The chi-square test was used to determine the association between categorical variables and mortality. Statistical analysis was conducted with IBM SPSS Statistics 25.0, and statistical significance was set at p<0.05. RESULTS: A total of 30 patients (CME and CVL=15 or conventional colectomies=15) were included in this study with mean age of 65 years. There was no statistical difference between the mean age of the two groups (p=0.355). Most of the patients were Malays (46.7%) followed by Chinese (43.3 %) and Indians (10.0%). The mean (SD) = 19 (9) number of lymph nodes harvested is more in CME and CVL groups which however is not statistically significant compared to the mean (SD) = 16 (9), number of lymph nodes in conventional colectomies. The duration of surgery is longer in CME and CVL groups (214 minutes) compared to conventional colectomies (188 minutes) but with no significant statistical difference. Most of the perioperative complications were similar in both groups with no significant statistical differences. CONCLUSION: CME and CVL are not inferior to conventional surgery in colon surgery in a tertiary centre. It should be considered since the advantages such as lymph node yield and median recurrence free survival are better with similar perioperative morbidity.

Mitigating mutual coupling effects on circular polarization for improved bandwidth in MIMO systems: A novel approach.

An improved mutual coupling compensation in circularly polarized (CP) multi-input multi-output (MIMO) dielectric resonator antenna (DRA) is presented in this paper. Using trimming approach, the mutual coupling (MC) between closely spaced DRA units at 0.3λ has been significantly reduced while axial ratio performance has been maintained. Mutual coupling reduction is obtained by trimming the DRA to ensure low mutual coupling below -20dB. The exclusive features of the proposed MIMO DRA include wide impedance matching bandwidth (BW), triple band circular polarization, and suppressed MC between the radiating elements. The impedance bandwidth matches perfectly with a triple band's 3 dB axial ratio (AR). It is designed with characteristic mode analysis with good agreement of the measurement that has been obtained. Using the probe feed method, the DRA and patch strip are coupled together to allow bandwidth widening of the pro-posed DRA. An impedance bandwidth of 34% at a lower frequency to around 2% at a higher frequency was achieved in all resonance frequencies. Thus, we refer to our newly designed DRA as a proposed method for effectively reducing the mutual coupling between DRAs. Additionally, the 3 dB AR bandwidth matched at 3.3 GHz, 4.6 GHz, and 6.3 GHz with a percentage of 11.66%, 3.04%, and 2.22% obtained at the three different frequencies. Note that the proposed DRA exhibits low mutual coupling (below -20 dB) at the targeted frequencies, which is suitable for better signal reception for MIMO applications. By computing, the metrics envelop correlation coefficient, diversity gain, channel capacity loss, and total active reflection coefficient, the MIMO performance of the proposed antenna is verified. The experiments show a close result between simulated and computed validation of the proposed DRA.

Implementing primary eye care in private practises in Malaysia: the challenges faced by optometrists.

OBJECTIVE: In Malaysia, optometrists' role in the private sector is limited compared to their counterparts elsewhere. Primary eye care (PEC) is still not widely offered in private practises despite its demand to reduce the public's eye morbidity. This study aims to explore the challenges perceived by the private sector optometrists in implementing PEC in Malaysia. MATERIALS AND METHODS: In-depth interview using semistructured open-ended questions were designed to explore the challenges of implementing PEC. Fifteen private optometrists across Malaysian were interviewed via purposive sampling until the data were saturated. The interviews were audio-recorded, transcribed and analysed. RESULTS: Four major themes emerged: working environment, support and recognition, self-sufficiency and customer influence. The first major theme identified a lack of time and equipment in the workplace as a barrier to PEC implementation. The second major theme acknowledges the lack of support and recognition for PEC practise from financial bodies, the government, Malaysian Optical Council (MOC) and other eye professionals. Meanwhile, some practising optometrists faced significant challenges due to their lack of self-sufficiency regarding skills, knowledge and confidence. The final major theme, customer influence, reflects the customer's role in shaping eye care delivery through their perception and acceptance of PEC. CONCLUSION: Each of the issues identified played a significant impact in impeding PEC implementation in Malaysia. This study is the first step toward developing tailored interventions to improve eye care delivery in Malaysia.

Development of a mental script for the mental practice of micro suturing: a methodological approach.

INTRODUCTION: Motor imagery and mental practice are important for the acquisition and mastery of surgical skills. The success of this technique relies on the use of a well-developed mental script. In this study, we shared how we developed a mental script for basic micro suturing training by using a low-fidelity rubber glove model. METHODS: This study applied the design and development research framework. Five expert surgeons developed a mental script by performing a cognitive walkthrough to repair a vertical opening in a rubber glove model, followed by hierarchical task analysis. A draft script was created, and its face and content validity assessed with a checking-back process. Twenty-eight surgeons used the Mental Imagery Questionnaire (MIQ) to assess the validity of the final script. RESULTS: The process of developing the mental script is detailed. The assessment by the expert panel showed the mental script had good face and content validity. The mean overall MIQ score was 5.2±1.1 (standard deviation), demonstrating the validity of generating mental imagery from the mental script developed in this study for micro suturing in the rubber glove model. CONCLUSION: The methodological approach described in this study is based on a design and development research framework to teach surgical skills. This model is inexpensive and easily accessible, addressing the challenges of reduced opportunities to practise surgical skills. However, although motor skills are important, the surgeon's other non-technical expertise is not addressed with this model. Thus, this model should act as one surgical training approach, but not replace it.

Integrating instructional design principles into surgical skills training models: an innovative approach.

OBJECTIVE: Surgical training programmes are evolving from time-based to competency-based schedules, which define expected learning outcomes in surgical knowledge, clinical and technical skills according to training levels. This article aims to review current models in surgical skills acquisition and to propose an integrative process-driven, outcomes-based model for surgical skills acquisition and mastery. DESIGN: A literature review was conducted on the theories of motor skills acquisition using PubMed, Web of Science and Google Scholar from 2010 to February 2020. The review was limited to theories and models on surgical skills acquisition and mastery. Four models of surgical skills acquisition were included: Fitts and Posner's three-stage model of motor skills acquisition, Bandura's social learning theory, Ericsson's deliberate practice model and Jeannerod's motor simulation theory. These models are deficient in that there is no universally accessible opportunity to practise the surgical procedure outside of the operating theatre and without access to physical simulators. RESULTS: We propose an innovative model that allows deliberate practice of the procedure without the need for expensive physical simulators, and provides an on-demand, self-directed practice by the trainees to achieve the level of mastery. This new model, which incorporates motor imagery and mental practice, augmented by deliberate practice, will provide an alternative training path for expert performance in surgical procedures. CONCLUSIONS: The innovative model provides a solution to the reduced opportunity for practice by surgical trainees to achieve mastery in surgical motor skills.

Nanoparticles carrying fingolimod and methotrexate enables targeted induction of apoptosis and immobilization of invasive thyroid cancer.

Metastatic tumors are the main cause of cancer-related death, as the invading cancer cells disrupt normal functions of distant organs and are nearly impossible to eradicate by traditional cancer therapeutics. This is of special concern when the cancer has created multiple metastases and extensive surgery would be too dangerous to execute. Therefore, combination chemotherapy is often the selected treatment form. However, drug cocktails often have severe adverse effects on healthy cells, whereby the development of targeted drug delivery could minimize side-effects of drugs and increase the efficacy of the combination therapy. In this study, we utilized the folate antagonist methotrexate (MTX) as targeting ligand conjugated onto mesoporous silica nanoparticles (MSNs) for selective eradication of folate receptor-expressing invasive thyroid cancer cells. The MSNs was subsequently loaded with the drug fingolimod (FTY720), which has previously been shown to efficiently inhibit proliferation and invasion of aggressive thyroid cancer cells. To assess the efficiency of our carrier system, comprehensive in vitro methods were employed; including flow cytometry, confocal microscopy, viability assays, invasion assay, and label-free imaging techniques. The in vitro results show that MTX-conjugated and FTY720-loaded MSNs potently attenuated both the proliferation and invasion of the cancerous thyroid cells while keeping the off-target effects in normal thyroid cells reasonably low. For a more physiologically relevant in vivo approach we utilized the chick chorioallantoic membrane (CAM) assay, showing decreased invasive behavior of the thyroid derived xenografts and an increased necrotic phenotype compared to tumors that received the free drug cocktail. Thus, the developed multidrug-loaded MSNs effectively induced apoptosis and immobilization of invasive thyroid cancer cells, and could potentially be used as a carrier system for targeted drug delivery for the treatment of diverse forms of aggressive cancers that expresses folate receptors.

Study on the physical and chemical composition of agro wastes for the production of 5-hydroxymethylfurfural.

Treated sludge, goat manure, sugarcane bagasse, empty fruit bunches of oil palm (EFBP) and dry leaves are agro wastes that have high potential for use as feedstocks for the production of 5-hydroxymethylfurfural (5-HMF). The focus of this study is to investigate the production of 5-HMF from agro wastes via co-hydrothermal (CHT) treatment and extraction. Present study include examine on agro waste's physical and chemical properties and also their thermal degradation behaviour. The analysis of the bio-oil products is conducted by FTIR and GC-MS. Co-hydrothermal experiments were conducted at a temperature of 300°C with an experimental time of 15min, followed by alcohol extraction. Highest carbon and hydrogen content are 45.94% and 6.49% (dry leaves) with maximum high heating value 18.39MJ/kg (dry leaves) and fix carbon value 6.60 (goat manure). Through CHT about 39% 5-HMF, 22.97% carboxylic acids, 0.97% of aromatic and 0.73% aldehyde obtained.

The synthetic molecules YK51 and YK73 attenuate replication of dengue virus serotype 2.

Dengue virus infection has been posing alarming economic and social burden on affected nations. It is estimated that 50-100 million dengue infections occur annually with over 2.5 billion people at risk for endemic transmission. In the effort to develop effective antiviral agents, we previously reported potential antiviral activities from selected array of natural products and compounds against dengue virus serotype 2 (DV2). In this study, we report the synthesis of two efficacious novel compounds, YK51 and YK73, and their activities against DV2 replication. Both compounds were chemically synthesised from nicotinic acid using a modified method for the synthesis of dihydropyridine. The products were tested with cell-based assays against DV2 followed by a serine protease assay. As a result, both YK51 and YK73 exhibited intriguing antiviral properties with EC50 of 3.2 and 2.4 µM, respectively. In addition, YK51 and YK73 were found to attenuate the synthesis of intracellular viral RNA and protect the switching of non-classic mechanism of protein translation. These compounds demonstrated inhibitory properties toward the activity of DV2 serine protease in a dose dependent manner. These findings demonstrate that both YK51 and YK73 serve as DV2 serine protease inhibitors that abrogate viral RNA synthesis and translation. Further investigation on these compounds to corroborate its therapeutic properties towards dengue is warranted.

Decidualization of the canine uterus: From early until late gestational in vivo morphological observations, and functional characterization of immortalized canine uterine stromal cell lines.

The apparent lack of classical mechanisms for maternal recognition of pregnancy is one of the most intriguing features of canine reproduction. Consequently, similar levels of circulating luteal steroids are observed in pregnant and non-pregnant dogs. However, the early pre-implantation canine embryo locally modulates uterine responses to its presence, facilitating the successful onset of pregnancy. As a part of this interaction, the canine uterus undergoes a species-specific decidualization. Maternal stroma-derived decidual cells develop, the only cells of the canine placenta expressing progesterone receptor (PGR). There exists an acute need for an in vitro stable cell line model for canine decidualization. Therefore, herein our goal was to establish, immortalize and characterize such a cell line. We immortalized three monolayer dog uterine stromal (DUS) cell lines by stably transfecting them with SV40Tag oncogene. Cells retained their mesenchymal character for over 30 passages, as evidenced by VIMENTIN staining. Genomic incorporation of the SV40Tag protein was confirmed by immunofluorescence and Western blot analyses. Cells submitted to a classical in vitro decidualization protocol (N6,2'-O-dibutyryladenosine-3',5'-cyclic monophosphate) revealed upregulated gene levels of selected major decidualization markers (e.g. PRLR, PGR, IGF1, PTGES). Additionally, the basic decidualization capability of PGE2 was demonstrated, revealing increased levels of, for example, PGR and PRLR gene expression, thereby implying its involvement in the progesterone-dependent decidualization in the canine uterus. In summary, our in vitro model with immortalized DUS cell line could serve as an ideal and unique model to study the underlying molecular and endocrine mechanisms of canine decidualization.

Room temperature ammonia sensing using tapered multimode fiber coated with polyaniline nanofibers.

We demonstrate an ammonia sensor composed of a tapered multimode fiber coated with polyaniline nanofibers that operates at room temperature (26°C). The optical properties of the polyaniline layer changes when it is exposed to ammonia, leading to a change in the absorption of evanescent field. The fiber sensor was tested by exposing it to ammonia at different concentrations and the absorbance is measured using a spectrophotometer system. Measured response and recovery times are about 2.27 minutes and 9.73 minutes, respectively. The sensor sensitivity can be controlled by adjusting the tapered fiber diameter and the highest sensitivity is achieved when the diameter is reduced to 20 µm.

Choroidal osteoma - case reports.

Choroidal osteoma is a rare disease. In this article four case histories were described. All were female and young patient. One patient had bilateral and other three had unilateral involvement. They had no family history. One patient reported at eye department in Bangabandhu Sheikh Mujib Medical University (BSMMU) and the other three patients reported in Bangladesh Eye Hospital. Choroidal osteoma is a benign tumor. It is diagnosed by fundoscopy, ocular B-scan ultrasonography, x-ray orbit, FFA, OCT and CT-scan of orbit. Most patients do not require treatment. Hemorrhage on the lesion suggests the presence of sub-retinal neovascularization which are typically treated with laser or intra-vitreal anti-VEGF.

Screening of antiviral activities in medicinal plants extracts against dengue virus using dengue NS2B-NS3 protease assay.

Dengue virus infects millions of people worldwide and there is no vaccine or anti-dengue therapeutic available. Screening large numbers of medicinal plants for anti-dengue activities is an alternative strategy in order to find the potent therapeutic compounds. Therefore, this study was designed to identify anti-dengue activities in nineteen medicinal plant extracts that are used in traditional medicine. Local medicinal plants Vernonia cinerea, Hemigraphis reptans, Hedyotis auricularia, Laurentia longiflora, Tridax procumbers and Senna angustifolia were used in this study. The highest inhibitory activates against dengue NS2B-NS3pro was observed in ethanolic extract of S. angustifolia leaves, methanolic extract of V. cinerea leaves and ethanol extract of T. procumbens stems. These findings were further verified by in vitro viral inhibition assay. Methanolic extract of V. cinerea leaves, ethanol extract of T. procumbens stems and at less extent ethanolic extract of S. angustifolia leaves were able to maintain the normal morphology of DENV2-infected Vero cells without causing much cytopathic effects (CPE). The percentage of viral inhibition of V. cinerea and T. procumbens extracts were significantly higher than S. angustifolia extract as measured by plaque formation assay and RT-qPCR. In conclusion, The outcome of this study showed that the methanolic extract of V. cinerea leaves and ethanol extract of T. procumbens stems possessed high inhibitory activates against dengue virus that worth more investigation.

Ototoxicity screening of patients treated with streptomycin using distortion product otoacoustic emissions.

OBJECTIVE: Pure tone audiometry (PTA) is currently widely used to monitor ototoxicity, but this method is time-consuming. Here we validate distortion product otoacoustic emission (DPOAE) as an instrument for early detection of ototoxicity. METHODS: A cohort study was performed on newly diagnosed tuberculosis patients who were treated with streptomycin. The patients underwent hearing assessment using conventional PTA and high-frequency DPOAE (8, 9 and 10 kHz) on days 0, 7, 14, 28 and 56 of streptomycin treatment. Detection of ototoxicity according to the duration of streptomycin treatment was compared between DPOAE and PTA. RESULTS: Of 96 newly diagnosed patients treated with streptomycin, 50 completed the study. During the treatment period, 62.5% of the patients had vertigo, while 37.5% complained of tinnitus. DPOAE detected ototoxicity in 47.7% of the cases at day 7, 66.0% at day 14, 70.0% at day 28 and 77.1% at day 56 of streptomycin treatment. The higher frequencies were affected more by ototoxicity, with significant differences at 8 vs. 9 kHz on all testing days and at 9 vs. 10 kHz except on days 7 and 56 (p < 0.001). Hearing loss was detected by PTA in 2.3% of patients on day 7, in 10.6% on day 14, in 22.0% on day 48 and in 29.2% on day 56. CONCLUSION: DPOAE is a sensitive tool that can detect early changes in the cochlea due to ototoxicity. Use of DPOAE rather than PTA to screen for ototoxicity could reduce screening time and would allow clinical monitoring of more patients.

Applications of physiologically based pharmacokinetic (PBPK) modeling and simulation during regulatory review.

Physiologically based pharmacokinetic (PBPK) modeling and simulation is a tool that can help predict the pharmacokinetics of drugs in humans and evaluate the effects of intrinsic (e.g., organ dysfunction, age, genetics) and extrinsic (e.g., drug-drug interactions) factors, alone or in combinations, on drug exposure. The use of this tool is increasing at all stages of the drug development process. This report reviews recent instances of the use of PBPK in decision-making during regulatory review. The examples are based on Center for Drug Evaluation and Research reviews of several submissions for investigational new drugs (INDs) and new drug applications (NDAs) received between July 2008 and June 2010. The use of PBPK modeling and simulation facilitated the following types of decisions: the need to conduct specific clinical pharmacology studies, specific study designs, and appropriate labeling language. The report also discusses the challenges encountered when PBPK modeling and simulation were used in these cases and recommends approaches to facilitating full utilization of this tool.

Role of peroxynitrite and recombinant human manganese superoxide dismutase in reducing ischemia-reperfusion renal tissue injury.

BACKGROUND: In an acute kidney transplant rejection rat model, we demonstrated that manganese superoxide dismutase (MnSOD) activity was significantly reduced and MnSOD was nitrated by peroxynitrite (ONOO(-)), resulting in tissue injury. We examined whether tissue injury was reduced after external supplementation of recombinant human MnSOD in a rat renal ischemia-reperfusion injury model. METHODS: Male Brown-Norway rats underwent dissection of the right kidney. The animals were divided into 3 groups. The controls had the left renal blood vessels clamped for 90 minutes to induce ischemia, followed by reperfusion for 16 hours. In the intraperitoneal administration group, MnSOD was administered 30 minutes before ischemia and immediately before reperfusion. In the sham group, neither ischemia nor reperfusion was performed. After reperfusion, blood was collected, the left kidney was dissected and renal function and tissue injury were evaluated. RESULTS: Serum creatinine and K(+), blood urea nitrogen, and aspartate aminotransferase activity decreased significantly, whereas serum Na(+) and renal function improved in the MnSOD group compared with the control and sham groups. On hematoxylin and eosin staining, the histological score indicated that acute tubular necrosis was significantly reduced by MnSOD administration. Periodic acid-Schiff staining was absent in the nonadministration group, whereas it persisted in the MnSOD group. In the proximal renal tubules a large proportion of anti-nitrotyrosine staining was present before but absent after MnSOD administration. CONCLUSIONS: MnSOD administration improved renal function and reduced tissue injury. It may also reduce tissue injury in acute kidney transplant rejection and other tissue injuries caused by similar molecular mechanisms.

The sternalis muscle in cadavers: anatomical facts and clinical significance.

The sternalis is an anomalous muscle located in the anterior wall of thorax and several past reports have described its presence with clinical implications. The sternalis muscle may be incidentally detected during routine cadaveric dissections and autopsies. We observed the presence of anomalous sternalis muscle on both sides of the anterior chest wall in 25 cadavers (n = 50), over a span of three years. Out of a 50 cases, we observed a single case of sternalis on the right side of the 55-year-old male cadaver (2%). The sternalis was found to be absent in the rest 49 cases (98%). The sternalis muscle displayed an oblique course in the anterior wall of the thorax. The muscle originated near the seventh costal cartilage extending obliquely upwards to insert into the second costal cartilage close to the sternum. The originating portion of the muscle was located at a distance of 3.5 cm lateral to the mid-sternal plane. The vertical length and the maximum width of the anomalous sternalis muscle measured 9 cm and 1.9 cm, respectively. The fibers of the muscle vertically ascended upwards. No other associated anomalies were observed in the same cadaver. The presence of sternalis muscle is considered to be a rare variation with no earlier studies being performed in the Malaysian population. The anomalous sternalis muscle may be important for reconstructive surgeons performing mastectomy and radiologists interpreting mammograms. Thus, the sternalis muscle may be academically, anthropologically and surgically important.

Maxillofacial trauma with emphasis on soft-tissue injuries in Malaysia.

Soft-tissue injuries with or without facial bone involvement are the most common presentation following maxillofacial trauma. The objective of this study was to look at the distribution, pattern and type of soft-tissue injury in relation to aetiology. Records of patients over a period of 5 years (1998-2002), who sustained maxillofacial injuries and were treated at Kajang Hospital, a secondary referral hospital, were reviewed. Out of 313 patients with maxillofacial injuries, 295 patients sustained soft-tissue injuries. Males (79%) between 21 and 30 years old (34%) were the majority of patients. Road-traffic accident was the main cause of soft-tissue injuries (75%) with motorcycle accident being the most frequent (40%). The upper lips (23%) and the lower lips (18%) were the most common extraoral site involved, while the labial mucosa and sulcular areas, both accounting for 21%, were the most common intraoral sites. Stringent road-traffic regulations should be practiced in developing countries, as morbidity arising from road-traffic accidents poses a national economic and social problem.

Use of hecate-chorionic gonadotropin beta conjugate in therapy of lutenizing hormone receptor expressing gonadal somatic cell tumors.

Improvement of cancer treatment is a major challenge of medical research. Despite the immense efforts made in the improvement of diagnosis and treatment, cancer remains a major concern and cause of morbidity and mortality. Most of the modern anti-neoplastic therapies have severe side effects, and tumor cells often develop drug resistance. There is promise in the new generation of treatments (gene therapy, immunotherapy, vaccines, etc.) that are under development, but the efficacies and side effects of such therapies have so far been disappointing. Receptor-based therapies are not new, but many normal cells also present the same receptors reducing the specificity of such approaches. Several lytic peptides have been investigated because of they appear to kill cancer cells due to changes of their membrane potential. Thus, linking receptor-specific ligands to lytic peptides is expected to augment the specificity of targeting and decrease the toxicity of lytic peptides on normal cells. One such polypeptide is hecate (an analogue to the bee venom main component, melittin) that preferentially kills cancer cells at low doses. When this peptide is fused with the 81-95 amino acid fragment of chorionic gonadotropin-beta (CGbeta) subunit (hecate-CGbeta), it targets cells expressing luteinizing hormone receptor (LHR), even at very low doses, or when LHR is expressed at low level. Our recent data showed that this peptide conjugate is efficient in destroying LHR-positive cells in xenografts and more importantly in transgenic mouse models developing LHR-positive somatic cell tumors in gonads. The mechanism of action of hecate-CGbeta after binding to LHR is destruction of cell membranes resulting in rapid cell death by necrosis with minimal side effects. This review summarizes our findings on the action of this novel peptide and considers the future potential of this family of targeting peptides in the treatment of neoplasias.

Application of the linear interaction energy method (LIE) to estimate the binding free energy values of Escherichia coli wild-type and mutant arginine repressor C-terminal domain (ArgRc)-l-arginine and ArgRc-l-citrulline protein-ligand complexes.

Protein-ligand binding free energy values of wild-type and mutant C-terminal domain of Escherichia coli arginine repressor (ArgRc) protein systems bound to L-arginine or L-citrulline molecules were calculated using the linear interaction energy (LIE) method by molecular dynamics (MD) simulation. The binding behaviour predicted by the dissociation constant (K(d)) calculations from the binding free energy values showed preferences for binding of L-arginine to the wild-type ArgRc but not to the mutant ArgRc(D128N). On the other hand, L-citrulline do not favour binding to wild-type ArgRc but prefer binding to mutant ArgRc(D128N). The dissociation constant for the wild-type ArgRc-L-arginine complex obtained in this study is in agreement with reported experimental results. Our results also support the experimental data for the binding of L-citrulline to the mutant ArgRc(D128N). These showed that LIE method for protein-ligand binding free energy calculation could be applied to the wild-type and the mutant E. coli ArgRc-L-arginine and ArgRc-L-citrulline protein-ligand complexes and possibly to other transcriptional repressor-co-repressor systems as well.

Localization of bovine serum albumin in double-walled microspheres.

Phase separation of binary blends of various combinations of poly (L-lactide) (PLA), and poly (D,L-lactide-co-glycolide) (PLGA), was investigated using differential scanning calorimetry (DSC). Based on this phase separation phenomenon, double-walled microspheres were fabricated. A model agent, bovine serum albumin (BSA) labeled with fluorescein isothiocyanate (FITC-BSA) was localized in each layer. Scanning electron microscopy (SEM) and fluorescence microscopy (FM) were used to assess the formation of double-walled microspheres and the localization of the drug, respectively. When a 1:1 polymer ratio was used, the FITC-BSA was localized in the outer layer. When the relative ratio of PLGA to PLA was increased to 3:1 using the same overall polymer concentration, the FITC-BSA was localized in the inner core. Release studies were carried out to evaluate the advantage of double-walled microspheres compared to single walled microspheres. Microspheres made with FITC-BSA localized in the inner core exhibited a significantly lower initial release rate compared to microspheres where the drug was located in the outer layer, or compared to microspheres made from PLA only. Hence microspheres with a double-walled morphology have the potential for therapeutic use where a high burst might be detrimental.