Lipid environment modulates processivity and kinetics of a presenilin homolog acting on multiple substrates in vitro

Intramembrane proteases (IPs) hydrolyze peptides in the lipid membrane. IPs participate in a number of cellular pathways including immune response and surveillance, and cholesterol biosynthesis, and they are exploited by viruses for replication. Despite their broad importance across biology, how activity is regulated in the cell to control protein maturation and release of specific bioactive peptides at the right place and right time remains largely unanswered, particularly for the intramembrane aspartyl protease (IAP) subtype. At a molecular biochemical level, different IAP homologs can cleave non-biological substrates, and there is no sequence recognition motif among the nearly 150 substrates identified for just one IAP, presenilin-1, the catalytic component of γ-secretase known for its involvement in the production of amyloid-β plaques associated with Alzheimer disease. Here we used gel-based assays combined with quantitative mass spectrometry and FRET-based kinetics assays to probe the cleavage profile of the presenilin homolog from the methanogen Methanoculleus marisnigri JR1 as a function of the surrounding lipid-mimicking environment, either detergent micelles or bicelles. We selected four biological IAP substrates that have not undergone extensive cleavage profiling previously, namely, the viral core protein of Hepatitis C virus, the viral core protein of Classical Swine Fever virus, the transmembrane segment of Notch-1, and the tyrosine receptor kinase ErbB4. Our study demonstrates a proclivity toward cleavage of substrates at positions of low average hydrophobicity and a consistent role for the lipid environment in modulating kinetic properties.

Zinc sulfide-chitosan hybrid nanoparticles as a robust surface for immobilization of Sillago sihama α-amylase

In the present study, zinc sulfide-chitosan hybrid nanoparticles synthesized by chemical deposition were used as a matrix for the immobilization of purified α-amylase extracted from Sillago sihama (Forsskal, 1775). In this regard, the size and morphological structure of zinc sulfide-chitosan hybrid nanoparticles before and after the stabilization process were evaluated using FT-IR, DLS methods, as well as SEM and TEM electron microscopy, and EDS analyses. Then, the efficiency of the immobilized enzyme was measured in terms of temperature, optimal pH, stability at the critical temperature, and pH values. Immobilization of α-amylase on zinc sulfide -chitosan hybrid nanoparticles increased the long-term stability, as well as its endurance to critical temperatures and pH values; however, the optimal temperature and pH values of the enzyme were not altered following the immobilization process. The kinetic parameters of the enzyme were also changed during immobilization. Enzyme immobilization increased the K_m, whereas decreased the catalytic efficiency (K_cat / K_m) of the immobilized enzyme compared with the free enzyme. These results are very important as, in most cases, enzyme immobilization reduces the activity and catalytic efficiency of enzymes. The nano-enzyme produced in this study, due to its high temperature, and pH stability, could be a good candidate for industrial applications, especially in the food industry.

O022 Application of customised 3D printed models to aid undergraduate teaching and surgical planning in hepatobiliary surgery

Introduction

3D-printing in maxillofacial surgery has been used for several years to construct bespoke prostheses prior to surgical procedures. This work aims to assess whether its role can be

expanded into undergraduate teaching and surgical planning in hepatobiliary surgery.

Methods

Four patient CT scans with liver and renal pathology were deemed eligible for printing. A computer aided design was constructed for each scan, segmenting the organ, lesion, and vasculature. One kidney and three liver models were printed. Production time of the models ranged from 31 to 106 hours. One liver model with the associated CT scan was shown to 20 doctors of varying experience. They were asked to complete a survey evaluating its potential in surgery, aiding patient education, and anatomy education. The remaining models were used in an anatomy tutorial for 6 medical students, who were requested to complete a pre-and-post-session survey evaluating the potential for the 3D models in anatomy education.

Results

An average rating from the NHS-staff survey was 6.9 for pre-operative planning, 8.65 for aiding anatomy education, and 9.15 for potential use in patient education. Following the tutorial with the models, 4 of the 6 students felt their overall understanding of liver anatomy improved. In particular, all students expressed increased confidence in hepatic segmentation anatomy.

Conclusion

Our work shows that 3D-printed models can provide benefit in aiding clinical teaching and patient information. Future work will focus on use of the models as an aid to patient education in an outpatient setting.

Take-home message

3D-printed models have a future in aiding anatomy education and hepatobiliary surgical planning. Further research can consolidate their applications.

254 Simulation Matrix: Using Virtual Reality to Help Medical Students Transition into Clinical Practice During COVID-19

Aim

The COVID-19 pandemic has greatly impacted on undergraduate surgical education, as traditional teaching methods have been compromised leading to hesitancy and anxiety amongst medical students. This project provided an alternative teaching method using virtual reality (VR) headsets reducing the impact of the restrictions caused by COVID-19.

Method

23 medical students were enrolled. Clinical scenarios were randomly allocated. Each student completed pre- and post-session questionnaires. Student anxiety and mental preparedness were assessed using a 5-point Likert scale. Paired t-tests were used to analyse impact, and one-sample t-tests were used to assess student perceptions of VR. Results are presented as mean and 95% confidence intervals.

Results

VR simulations were found to have significantly increased clinical confidence in managing acutely unwell patients (0.91±0.39 points; p<0.0001) and improved mental preparedness to work in clinical setting (0.52±0.48 points; p=0.036). Our study also showed that VR simulation reduced students’ anxiety in managing acutely unwell patients (0.78±0.43 points; p=0.0011). 95.7% students strongly agreed that VR provides a psychologically safe training environment, and overall agreement was highly significant (mean score: 4.96±0.09, p<0.0001). 91.3% strongly agreed that VR training is a useful tool to help mental preparation for transition into clinical practice, and overall agreement was highly significant (mean score: 4.87±0.19, p<0.0001).

Conclusions

VR simulation can significantly improve student experience of, and mental preparedness, for transitioning into clinical practice. We would advocate regular use of VR headsets within the rapidly evolving world of surgical education.

714 An Evaluation of The Discontinuation of Tamsulosin and Finasteride Post Transurethral Resection of The Prostate (TURP) At UHL

Aim

A significant proportion of men suffer from lower urinary tract symptoms (LUTS) secondary to prostatic enlargement. If medical management of BPH fails surgical transurethral resection of the prostate maybe required. The continuation of pharmacological therapy post operatively is redundant, however it was noted that several patients remained on these medications post TURP. The aim of this project was to identify if patients following surgical intervention were discontinued from preexisting medications that became redundant post operatively.

Method

A retrospective analysis was performed of patients who underwent TURPs between July- December 2019 within the University Hospitals of Leicester NHS trust to assess if patients preexisting medications used for the treatment of LUTS were discontinued post operatively.

Results

In the above time frame, 104 TURPs were performed in the trust. Out of these, 89 men were already on 5-alpha reductase inhibitors and/or alpha blocker, predominantly tamsulosin and finasteride. Of the 89 men, only 46 were given a clear instruction to stop these drugs on discharge.

Conclusions

Continuation of the above medication is unnecessary post TURPs with potentially avoidable side effects for patients and an unnecessary expense. A series of changes were implemented to improve practice. These will be reevaluated on the recommencement of TURPs following the covid-19 pandemic.

Overtime trend of thyroid hormones and thyroid autoimmunity and ovarian reserve: a longitudinal population study with a 12-year follow up

BACKGROUND

Ovarian reserve, vital for reproductive function, can be adversely affected by thyroid diseases. Despite alternations of thyroid hormones with ageing, data on interactions between the overtime trend of thyroid functions and ovarian reserve status has rarely been reported. We aimed to examine the overtime trend of thyroid hormones, thyroid peroxidase antibody (TPO Ab) and their associations with ovarian reserve status, identified by levels of age specific anti-mullerian hormone (AMH) in reproductive aged women, who participated in 12-year cohort of Tehran Thyroid Study (TTS).

METHODS

Reproductive age women(n = 775) without any thyroid disease or ovarian dysfunction were selected from the Tehran Thyroid Study cohort. Participants were divided into four age specific AMH quartiles (Q1-Q4), Q1, the lowest and Q4, the highest. AMH was measured at the initiation of study and thyroid stimulating hormone (TSH), free T4 (FT4), and TPO Ab were measured at baseline and at three follow up visits.

RESULTS

At baseline, there was no statistically significant difference in thyroid hormones between women of the four quartiles, although TPO Ab levels were higher in women of Q1. During the follow ups, FT4 was decreased in all quartiles (p < 0.05), whereas TPO Ab increased in Q1 (p = 0.02). Odds ratio of overall TPO Ab positivity in women of Q1 was 2.08 fold higher than those in Q4. (OR: 2.08, 95%CI: 1.16, 3.72; p = 0.01).

CONCLUSION

Women with the lowest ovarian reserves had higher levels of TPO Ab, with a positive trend of this antibody overtime in comparison to other quartiles, indicating that this group may be at a higher risk of hypothyroidism over time.

Abstract P4-01-12: Optical imaging of breast density correlates with magnetic resonance imaging in patients undergoing neoadjuvant chemotherapy

Background: In addition to being a strong risk factor for breast cancer, data from recent studies suggests that breast density changes correlate with response to preventative or adjuvant tamoxifen treatment for breast cancer. Breast density may be a surrogate biomarker for survival and indication of the need for additional treatments such as radiotherapy. However, quantitative methods to assess breast density in the clinic are limited. In this study, we assess how Diffuse Optical Spectroscopic Imaging (DOSI) may be used to evaluate and understand changes in breast density in patients undergoing neoadjuvant chemotherapy.

Methods: DOSI was used to measure hemodynamic and metabolic information from the contralateral normal breast of 28 breast cancer patients undergoing neoadjuvant chemotherapy. DOSI uses near-infrared light to determine absolute tissue molar concentrations of oxyhemoglobin (ctO2Hb), deoxyhemoglobin (ctHHb), water, and lipid content without requirement of an exogenous contrast agent. DOSI measurements were compared to 3.0T MRI measured fibroglandular density before and during therapy.

Results: Water (r = 0.843; P&lt;0.001), ctHHb (r = 0.785; P = 0.003), and lipid (r = -0.707; P = 0.010) concentration measured with DOSI correlated strongly with MRI-measured density before therapy. During neoadjuvant treatment measured at ∼90 days after treatment commenced, significant reductions were observed in ctO2Hb for pre- (-20.0%; 95% confidence interval (CI), -32.7 to -7.4) and postmenopausal subjects (-20.1%; 95% CI, -31.4 to -8.8), and water concentration for premenopausal subjects (- 1.9%; 95% CI, -17.1 to -6.7) compared to baseline. Lipid content increased slightly in premenopausal subjects (3.8%; 95% CI, 1.1 to 6.5) and water increased slightly in postmenopausal subjects (4.4%; 95% CI, 0.1 to 8.6). Percentage change in water at the end of therapy compared with baseline correlated strongly with percentage change in MRI-measured density (r = 0.864; P = 0.012).

Discussion: For this patient cohort, non-invasive optical measurement may provide an assessment of breast density and yield additional information that complements MRI and mammography techniques. We demonstrate a strong baseline correlation between water and ctHHb with breast density, reflecting the increased water content and rate of metabolism in fibroglandular breast tissue. Significant changes in optical markers for vascular density and supply (ctO2Hb and water) are observed during treatment. A significant decrease in ctO2Hb is observed in both menopausal groups. The steady reduction of ctO2Hb without a corresponding decrease in ctHHb suggests that chemotherapy agents act directly on the normal breast tissue, perhaps by causing a reduction of perfusion. The greater reduction in breast-tissue water in premenopausal subjects suggests that chemo-reduced ovarian hormone levels may exert a role in reducing breast-tissue density. Although from a limited patient dataset, these results suggest that DOSI may provide new functional indices of breast density based on hemoglobin and water that could be used at the bedside to assess response to therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-12.

[Evaluation of urinary metanephrines for the diagnosis of pheochromocytoma]

OBJECTIVE

evaluate the assay of urinary metanephrines in diagnosis of pheochromocytoma (PH) and determine diagnostic cut-off values.

METHODS

this is a retrospective study about 87 patients suspected of pheochromocytoma,whose of 24-h urinary fractionated metanephrine was measured. These cases were collected from Internal Medecine Departments (A and B) at Charles Nicolle's Hospital. Two groups of patients were studied: a pheochromocytoma group (n=33) with a histologically-proven pheochromocytoma and a control group of 54 patients. Receiver Operating Characteristic (ROC) curves were used to determine the best sensitivities and specificities.

RESULTS

The analysis of biological parameters showed that means and standard deviation of urinary fractionated metanephrines in pheochromocytoma group were significantly higher than those of control group. Sensitivity and specificity of urinary normetanephrine test (95% and 98.1% respectively) were higher than those of urinary metanephrine and 3-methoxytyramine. A correlation between urinary normetanephrine and tumor size of pheochromocytoma was found.

CONCLUSION

Urinary fractionated metanephrines is an efficient biochemical test for the diagnosis of pheochromocytoma.

Morphology, seasonality and phylogeny of Zschokkella soleae sp. n. (Myxozoa, Myxosporea) parasite of Solea solea (L.) (Pleuronectiformes, Soleidae) from Ghar El Melh Lagoon, Tunisia

A new Myxosporea, Zschokkella soleae sp. n., was found in the gall bladder and the bile of common sole, Solea solea (L.), from Ghar El Melh Lagoon in north-east Tunisia. This is the first record for the presence of Zschokkella species in Tunisian waters. The parasite's plasmodia are polysporic with variable size and shape. Some plasmodia appeared attached to the gall bladder epithelium while others were found free in bile. Mature spores are ellipsoidal in frontal view 13.8±0.38 μm long and 10.86±0.40 μm wide with two equal size spherical polar capsules 3.6±0.43 μm in size. The prevalence of infection seems to correlate with host size and changes over the year with maximum percentage in summer. Based on the 18S rDNA sequence data, Z. soleae sp. n. is readily distinguishable from other myxozoan DNA sequences in GenBank. Phylogenetically, the new species is placed in the freshwater Myxidium clade including several Zschokkella spp. infecting the gall bladder. Morphology, histology as well as DNA sequence analysis indicate that the examined species differs from all previously described Zschokkella species.

Aerobic training programs and glycemic control in diabetic children in relation to exercise frequency

AIM

The aim of this study was to assess the effect of an aerobic training on glycemic control and lipid profile in diabetic children.

METHODS

Thirty-three children with type 1 diabetes mellitus (T1DM) were equally divided in three groups. The control group (CG) did not perform any training intervention during the period of the investigation and the subjects were instructed to continue with their daily lifestyle patterns. The second group (G1) and the third group (G2) completed a six-month aerobic training programs. During the period of the investigation, G1 participated in one daily session (~60 min) of aerobic exercise twice weekly, while G2 performed in the form of daily session four times a week (~60 min). HbA1c and lipid profile were measured before training intervention, then after three and six months.

RESULTS

The three-month periods was without significant changes of HbA1c in the two groups but significantly increased high-density lipoprotein cholesterol (HDL-C) in G1 (P<0.05). In G2, an increase of HDL-C was accompanied by a decrease of serum triglyceride (TG) (P<0.05). After six months, only HDL-C and TG levels were significantly lower in G1 (P<0.01), while in G2 HDL-C increased (68.8±5.7 mg/dL vs. 56.7 ±7.2 mg/dL; P<0.01), low-density lipoprotein cholesterol (LDL-C) (69.2±8.5 mg/dL vs. 81.6±11.8 mg/dL; P<0.01), TG concentrations decreased (60.7±6.9 mg/dL vs. 77.4±9.3 mg/dL; P<0.01) and HbA1c was significantly lower (6.8±1.1% vs. 8.2±1.5%; P<0.05), comparatively to those before training.

CONCLUSION

However, the six-month periods showed that children exercising more than two times weekly significantly improved HbA1c and lipid profile. These results must encourage children with T1DM to regularly practice sporty activities for long periods.

Abstract P2-02-11: Evaluation of Tumor Response Using 3T Breast MRI Following Neoadjuvant Albumin-Bound Paclitaxel and Carboplatin with Bevacizumab or Trastuzumab

PURPOSE: MRI is known as the most accurate imaging modality for evaluating the extent of residual disease following neoadjuvant chemotherapy (NAC). Although in general breast MRI is done at 1.5T, 3T can provide a better signal-to-noise ratio and may be more sensitive to detect residual disease. In this study the diagnostic performance of 3T MRI for NAC response was investigated.

METHODS AND MATERIALS: In a period of 30 months, 42 NAC patients (29-83 y/o, mean 50 y/o) who received at least three MRI scans before, during and after therapy, and had surgery after completing NAC were analyzed in this study. The NAC protocol included albumin-bound paclitaxel, carboplatin and trastuzumab for HER-2 positive patients (N= 15), or bevacizumab for HER-2 negative patients (N=27). Some patients received doxorubicin and cyclophosphamide, bi-weekly for 4 cycles, as clinically indicated. Twenty-eight lesions were mass types and 14 showed non-mass-like enhancements. The residual tumor size was determined using the RECIST criteria, by measuring the longest dimension shown on MRI. When there was no enhancement (or, with a faint enhancement equal to the background normal tissue enhancement), the case was determined as complete clinical response (CCR). Pathological complete response (pCR) was defined as no residual invasive cancer cells, with or without DCIS. In cases with residual invasive cancer, the pathological size was determined as the longest dimension, either the longest dimension on H&E-stained slide or from the number of blocks (each 5 mm) where the malignant invasive tumor was detected, whichever was greater. For residual tumor showing as scattered cancer cells/nests, the longest dimension was estimated from the involved blocks.

RESULTS: MRI diagnosed 12 complete clinical response and 30 cases with residual cancers. In pathological examination, 12 were pCR (29%). Overall, comparing MRI diagnosis to pCR diagnosis, there were 27 true positive, 9 true negative, 3 false negative, and 3 false positive. The three false positive cases all had residual DCIS-so although MRI did not predict pCR it correctly diagnosed residual DCIS. The three false negative cases were all non-mass lesions, in which pathology showed scattered small cancer foci in 3, 14, and 14 cm areas, respectively. The sensitivity, specificity, and accuracy of MRI were 90%, 75%, and 86%. Overall, the correlation between MRI and pathologic size was higher for mass lesions than for non-mass-like lesions (r=0.80 vs. r=0.67), and similar between Her-2 positive and negative lesions (r=0.82 vs. r=0.84). The discrepancy between MRI and pathological size was larger for non-mass lesions than for mass lesions (0.6-14 cm vs. 0-3 cm).

CONCLUSIONS: Similar to 1.5T, high resolution 3T MRI has limitations for the non-mass-like lesions that break into small foci and scattered cells. This might be due to that small tumor foci have lowered angiogenic activity, limiting MR contrast agent uptake, thus lowering the detection rate. For mass lesions, MR residual tumor size was highly correlated with pathological size. Understanding the accuracy and limitations of 3T MRI for NAC patients may aid in designing an improved NAC protocol and a better surgical planning.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-02-11.

Long-term outcomes with concurrent carboplatin, paclitaxel and radiation therapy for locally advanced, inoperable head and neck cancer

BACKGROUND

Our goal was to evaluate long-term efficacy outcomes of patients with squamous cell carcinoma of the head and neck (SCCHN) treated with carboplatin, paclitaxel (Taxol) and radiotherapy.

PATIENTS AND METHODS

We conducted a phase II trial in inoperable patients with locally advanced SCCHN. Carboplatin 100 mg/m(2) and paclitaxel 40 mg/m(2) were administered i.v. once a week during external beam radiation therapy (180 cGy per fraction) for 6-7 weeks. Interstitial brachytherapy was used as a boost in selected patients with primary malignancies of the oral cavity and the oropharynx.

RESULTS

Fifty-five patients were enrolled. Fifty-two patients (95%) had stage IV and 51 (93%) had technically unresectable disease; 62% had an oropharyngeal primary site. Twenty-one patients underwent brachytherapy boost. Grade 3 or 4 mucositis occurred in 30% of patients. One death occurred during treatment that was related to complications of gastrostomy tube placement. Forty of 50 assessable patients (80%) had an objective response, with a complete response rate of 52%. With a median follow-up of 69 months for surviving patients, the 5-year progression-free survival was 36% and the 5-year overall survival was 35%. Two of the 18 long-term survivors of >50 months were gastrostomy tube feeding dependent. Patients undergoing brachytherapy boost (n = 21) had similar outcomes compared with the rest of the patients. In multivariate analysis, baseline hemoglobin levels and N stage were predictive of survival.

CONCLUSION

Treatment with concurrent carboplatin, paclitaxel and radiation is safe and offers curative potential for poor prognosis patients with locally advanced SCCHN.

Long-term outcomes with concurrent carboplatin, paclitaxel, and radiation therapy in locally advanced, inoperable head and neck cancer

6032

Background: Our goal was to evaluate long-term outcomes of patients with squamous cell carcinoma of the head and neck (SCCHN) treated with carboplatin, paclitaxel, and radiotherapy. Methods: We conducted a phase II trial in inoperable patients with locally advanced SCCHN. Carboplatin 100 mg/m2 and paclitaxel 40 mg/m2 were administered intravenously once a week during external beam radiotherapy (once daily, 180 cGy/fraction) for 6–7 weeks. Interstitial brachytherapy was used as a boost in selected patients with primary malignancies of the oral cavity and the oropharynx. Results: 55 patients were enrolled. 52 patients (95%) had stage IV and 51 (93%) had technically unresectable disease; 62% had an oropharyngeal primary site. 21 patients underwent brachytherapy boost. Grade 3 or 4 mucositis occurred in 30% of patients. One death occurred during treatment; it was related to complications of gastrostomy tube (G-tube) placement. Forty of 50 evaluable patients (80%) had an objective response, with a complete response rate of 52%. With a median follow-up of 69 months years for surviving patients, the 5-year progression-free survival (PFS) was 36% and the 5-year overall survival (OS) was 35%. Two of the 18 long-term survivors of >50 months were G-tube feeding dependent. Patients undergoing brachytherapy boost (n=21) had similar outcomes compared with the rest of the patients. In multivariate analysis, baseline hemoglobin levels and N stage were predictive of survival. Conclusion: Treatment with concurrent carboplatin, paclitaxel and radiation is safe and offers curative potential for poor prognosis patients with locally advanced SCCHN.

No significant financial relationships to disclose.

Establishment of multiple sublineages of H5N1 influenza virus in Asia: implications for pandemic control

Preparedness for a possible influenza pandemic caused by highly pathogenic avian influenza A subtype H5N1 has become a global priority. The spread of the virus to Europe and continued human infection in Southeast Asia have heightened pandemic concern. It remains unknown from where the pandemic strain may emerge; current attention is directed at Vietnam, Thailand, and, more recently, Indonesia and China. Here, we report that genetically and antigenically distinct sublineages of H5N1 virus have become established in poultry in different geographical regions of Southeast Asia, indicating the long-term endemicity of the virus, and the isolation of H5N1 virus from apparently healthy migratory birds in southern China. Our data show that H5N1 influenza virus, has continued to spread from its established source in southern China to other regions through transport of poultry and bird migration. The identification of regionally distinct sublineages contributes to the understanding of the mechanism for the perpetuation and spread of H5N1, providing information that is directly relevant to control of the source of infection in poultry. It points to the necessity of surveillance that is geographically broader than previously supposed and that includes H5N1 viruses of greater genetic and antigenic diversity.

[Epidemiologic data in renal lithiasis in adults]

The morpho-costitutional analysis of 574 urinary lithiasis emitted by tunisean adults permitted to define an épidemiology's profile. This resemble to the épidemiology's profile of under-developed conry: Amore raised frequency of the renal lithiasis at the man than at the woman with a sec ratio of 2.4. An average age of +14 years with a peak to 4th decade in 2 sexes. The upper localitation of the calculi is founded in 94% cases. The fréquency of the relapses, the mode of expulsion and the size of calculi are différent of those published in the litérature. Probably because the time of study which last 4 years is too short, so it don't enable us to find a result like the literature. The surgery is the mode of most fréquent élimination (51%). This s dû to the présence great size calculi in our popûlation and to the récent introduction of the lithotritie in our country.

Lipase activity in germinating sunflower seedlings

Studying lipase in germinating sunflower seedlings, we looked for an activator of the lipolytic activity. In the presence of 1.25 mM ATP, the enzyme activity increased 2-fold. Lipid-body lipase solubilization was realized using two detergents: Tween 80 and CHAPS. Lipolytic activity was increased 10-fold in the presence of 2% (w/v) CHAPS, showing the probable 'complexity' of the enzyme. Looking for the possible lipolytic activity of the 10000 g pellet we detected the presence of the enzyme. The pellet extract was mixed, in a range of concentrations, with the oil-body fraction. The resulting lipolytic activity was 4-fold higher. These results give clues as to the subcellular distribution of lipase and its intracellular transport.

Receptor tyrosine phosphatases regulate axon guidance across the midline of the Drosophila embryo

Neural receptor-linked protein tyrosine phosphatases (RPTPs) are required for guidance of motoneuron and photoreceptor growth cones in Drosophila. These phosphatases have not been implicated in growth cone responses to specific guidance cues, however, so it is unknown which aspects of axonal pathfinding are controlled by their activities. Three RPTPs, known as DLAR, DPTP69D, and DPTP99A, have been genetically characterized thus far. Here we report the isolation of mutations in the fourth neural RPTP, DPTP10D. The analysis of double mutant phenotypes shows that DPTP10D and DPTP69D are necessary for repulsion of growth cones from the midline of the embryonic central nervous system. Repulsion is thought to be triggered by binding of the secreted protein Slit, which is expressed by midline glia, to Roundabout (Robo) receptors on growth cones. Robo repulsion is downregulated by the Commissureless (Comm) protein, allowing axons to cross the midline. Here we show that the Rptp mutations genetically interact with robo, slit and comm. The nature of these interactions suggests that DPTP10D and DPTP69D are positive regulators of Slit/Roundabout repulsive signaling. We also show that elimination of all four neural RPTPs converts most noncrossing longitudinal pathways into commissures that cross the midline, indicating that tyrosine phosphorylation controls the manner in which growth cones respond to midline signals.

Results of multifield conformal radiation therapy of nonsmall-cell lung carcinoma using multileaf collimation beams

A five-field conformal technique with three-dimensional radiation therapy treatment planning (3-DRTP) has been shown to permit better definition of the target volume for lung cancer, while minimizing the normal tissue volume receiving greater than 50% of the target dose. In an initial study to confirm the safety of conventional doses, we used the five-field conformal 3-DRTP technique. We then used the technique in a second study, enhancing the therapeutic index in a series of 42 patients, as well as to evaluate feasibility, survival outcome, and treatment toxicity. Forty-two consecutive patients with nonsmall-cell lung carcinoma (NSCLC) were evaluated during the years 1993-1997. The median age was 60 years (range 34-80). The median radiation therapy (RT) dose to the gross tumor volume was 6,300 cGy (range 5,000-6,840 cGy) delivered over 6 to 6.5 weeks in 180-275 cGy daily fractions, 5 days per week. There were three patients who received a split course treatment of 5,500 cGy in 20 fractions, delivering 275 cGy daily with a 2-week break built into the treatment course after 10 fractions. The stages of disease were II in 2%, IIIA in 40%, IIIB in 42.9%, and recurrent disease in 14.3% of the patients. The mean tumor volume was 324.14 cc (range 88.3-773.7 cc); 57.1% of the patients received combined chemoradiotherapy, while the others were treated with radiation therapy alone. Of the 42 patients, 7 were excluded from the final analysis because of diagnosis of distant metastasis during treatment. Two of the patients had their histology reinterpreted as being other than NSCLC, 2 patients did not complete RT at the time of analysis, and 1 patient voluntarily discontinued treatment because of progressive deterioration. Median follow-up was 11.2 months (range 3-32.5 months). Survival for patients with Stage III disease was 70.2% at 1 year and 51.5% at 2 years, with median survival not yet reached. Local control for the entire series was 23.3+/-11.4% at 2 years. However, for Stage III patients, local control was 50% at 1 year and 30% at 2 years. Patients who received concurrent chemotherapy had significantly improved survival (P = 0.002) and local control (P = 0.004), compared with RT alone. Late esophageal toxicity of > or =Grade 3 occurred in 14.1+/-9.3% of patients (3 of 20) receiving combined chemoradiotherapy, but in none of the 15 patients treated with RT alone. Pulmonary toxicity limited to Grades 1-2 occurred in 6.8% of the patients, and none developed > or =Grade 3 pulmonary toxicity. Patients with locally advanced NSCLC, who commonly have tumor volumes in excess of 200 cc, presenta challenge for adequate dose delivery without significant toxicity. Our five-field conformal 3-DRTP technique, which incorporates treatment planning by dose/volume histogram (DVH) was associated with minimal toxicity and may facilitate dose escalation to the gross tumor.

Inhibition of peridural fibrosis after laminectomy using low-dose external beam radiation in a rat model

OBJECTIVE

Clinical studies have revealed a significant association between the presence of extensive postlumbar discectomy peridural scar formation and the reoccurrence of low back and radicular pain. Low-dose perioperative radiation therapy has been shown to inhibit scar formation. Its effect on peridural fibrosis, however, has not been studied.

METHODS

Thirty male Sprague-Dawley rats underwent L5 laminectomies. Ten rats each received a single fraction of 700-cGy external beam radiation to the lumbar spine 24 hours before surgery; 10 rats each received 700 cGy 24 hours after surgery. The remaining 10 rats served as a control group. All of the rats were killed 30 days after surgery. The spines were harvested, and axial histological sections through the laminectomy defect were evaluated. Each specimen was scored for extent, density, and arachnoidal involvement by fibrosis.

RESULTS

There was a statistically significant difference between the treatment and control groups regarding the extent of fibrosis along the dura (P < 0.001), the density of fibroblasts (P < 0.005), and the arachnoid involvement (P < 0.01). There was no difference in fibrosis reduction between the groups receiving pre- and postlaminectomy radiation.

CONCLUSION

Low-dose external beam radiation therapy administered before or after laminectomy in a rat model significantly decreases the extent, density, and arachnoidal involvement of peridural fibrosis. This technique may improve the outcome of patients who undergo reoperations for recurrent radicular and/or low back pain after successful lumbar discectomy in whom there is a significant amount of peridural fibrosis.

Epidemiology of Trypanosoma evansi infection in crossbred dairy cattle in Malaysia

An investigation into the epidemiology of Trypansoma evansi infection in crossbred dairy cattle was conducted for a period of 12 months on a dairy cattle farm in Penninsular Malaysia. The prevalence of parasitaemia was highest in lactating animals (13.4%), followed by those in the dry herd (8.8%), late pregnant animals (8.1%), early pregnant animals (4.7%), calves (0.3%) and heifers (0.2%). The prevalence of antigenaemia was highest in the lactating animals (54.7%), followed by that in dry animals (53.7%), heifers (51.1%), late pregnant animals (47.7%), early pregnant animals (46.5%) and calves (24.2%).

Local periocular vaccination protects against eye disease more effectively than systemic vaccination following primary ocular herpes simplex virus infection in rabbits

Vaccination of experimental animals can provide efficient protection against ocular herpes simplex virus type 1 (HSV-1) challenge. Although it is suspected that local immune responses are important in protection against ocular HSV-1 infection, no definitive studies have been done to determine if local ocular vaccination would produce more efficacious protection against HSV-1 ocular challenge than systemic vaccination. To address this question, we vaccinated groups of rabbits either systemically or periocularly with recombinant HSV-2 glycoproteins B (gB2) and D (gD2) in MF59 emulsion or with live KOS (a nonneurovirulent strain of HSV-1). Three weeks after the final vaccination, all eyes were challenged with McKrae (a virulent, eye disease-producing strain of HSV-1). Systemic vaccination with either HSV-1 KOS or gB2/gD2 in MF59 did not provide significant protection against any of the four eye disease parameters measured (conjunctivitis, iritis, epithelial keratitis, and corneal clouding). In contrast, periocular vaccination with gB2/gD2 in MF59 provided significant protection against conjunctivitis and iritis, while ocular vaccination with live HSV-1 KOS provided significant protection against all four parameters. Thus, local ocular vaccination provided better protection than systemic vaccination against eye disease following ocular HSV-1 infection. Since local vaccination should produce a stronger local immune response than systemic vaccination, these results suggest that the local ocular immune response is very important in protecting against eye disease due to primary HSV-1 infection. Thus, for clinical protection against primary HSV-1-induced corneal disease, a local ocular vaccine may prove more effective than systemic vaccination.

Considerations in optimizing radiation therapy for non-small cell lung cancer

Irradiation therapy for lung cancer is mostly restricted to conventional methods. To improve therapeutic ratio, we have combined a treatment planning and a gene therapy approach. Three-dimensional conformal radiotherapy is described as carried out by methods of gene therapy for radiation protection using the manganese-superoxide-dismutase transgene delivered by inhalation gene transfer. These methods may improve therapeutic outcomes in lung cancer.

Klumpfuss, a putative Drosophila zinc finger transcription factor, acts to differentiate between the identities of two secondary precursor cells within one neuroblast lineage

The approximately 300 distinct neurons comprising each hemineuromere of the Drosophila embryonic central nervous system are derived from a segmentally reiterated array of approximately 30 progenitor cells, neuroblasts (NBs). Each NB has a unique identity and undergoes repeated cell divisions to produce several smaller secondary precursor cells, ganglion mother cells (GMCs); each GMC divides once to produce two neurons and/or glia, thereby generating a specific lineage of neurons/glia. Understanding the generation of neuronal diversity requires not only elucidation of the molecules and mechanisms that specify NB identity but also those that act to differentiate between the cell types produced within one NB lineage. Here we show that the Drosophila Zn finger protein Klumpfuss (Klu), which shows sequence similarities to the mammalian Wilm's tumor suppressor (WT-1), acts to differentiate between the identities of the first two secondary precursor cells produced from one NB lineage. Klu is expressed in the NB4-2 lineage only after two rounds of NB cell division, in the second born GMC (GMC4-2b). In loss-of-function mutant embryos, the first born GMC (GMC4-2a) as well as its progeny neurons are duplicated; we show that this duplication of the GMC4-2a sublineage arises because GMC4-2b adopts the identity of GMC4-2a and divides to produce the GMC4-2a progeny. Moreover, when Klu is ectopically expressed in GMC4-2a, it fails to acquire its normal identity and fails to produce correctly specified progeny. klu therefore acts to specify the identity of GMC4-2b and to make it distinct from GMC4-2a. Our findings further suggest that the determination of GMC cell fate occurs in two steps; the initial GMC identity is the consequence of inheritance from the maternal NB, however, the subsequent stabilization of this identity requires functions like klu in the GMC.

Chemoradiotherapy in non-small cell lung cancer: paclitaxel/carboplatin/radiotherapy in regionally advanced disease

Based on superior results observed with combined-modality therapy over radiotherapy alone and on the authors' previous work with carboplatin and standard daily thoracic radiotherapy in patients with advanced, unresectable non-small cell lung cancer, a phase II study was designed to incorporate radiosensitizing doses of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) into the carboplatin/radiotherapy regimen, to improve the therapeutic index and define the toxicities. Thirty-two patients have been entered. Paclitaxel 45 mg/m2/wk was administered over 3 hours prior to carboplatin (100 mg/m2/wk) and thoracic radiotherapy (1.8 Gy/d 5 days a week; total dose, 60 to 65 Gy). No grade 4 toxicities occurred. Seven patients had chemotherapy doses delayed because of grade 3 neutropenia, and one patient had grade 3 mucositis/esophagitis that required hospitalization. Median survival has not yet been reached, and all patients are being followed. These preliminary data demonstrate the feasibility of combined concurrent chemoradiotherapy, with acceptable toxicities. Further investigation is needed to optimize carboplatin dosage with adaptive control using formulas based on pharmacokinetics and pharmacodynamics. Full-dose induction chemotherapy regimens to maximize the systemic effects of chemotherapy should precede concurrent chemoradiotherapy in future studies.

Australian-Indonesian collaboration in veterinary arbovirology--a review

Australian-Indonesian collaboration in veterinary development programs has led to significant advances in the study of arboviruses. This paper reviews the resulting knowledge of arboviral infections of livestock in Indonesia. The first recognized arboviral disease of animals in Indonesia was bovine ephemeral fever. Serology indicates that the virus is widespread, as are related rhabdoviruses. Local sheep appear resistant to bluetongue disease, but imported sheep have suffered mortalities. Bluetongue viral serotypes 1, 7, 9, 12, 21 and 23 have been isolated from sentinel cattle; 1, 21 and 23 at widely separate locations. Bluetongue serotype 21 has been isolated from Culicoides spp. Serological reactors to Akabane virus are widespread, as are reactors to the flavivirus group. Japanese encephalitis, isolated from sentinel pigs, is the flavivirus of most veterinary importance but the limit of its easterly distribution is unknown. Many of the arboviruses present in Indonesia are also present in Australia and elsewhere in Asia. Their patterns of mobility among countries in the region are largely undescribed, but there are opportunities for further regional collaboration.

Protection against herpes simplex virus-induced eye disease after vaccination with seven individually expressed herpes simplex virus 1 glycoproteins

PURPOSE

To compare the efficacy of each of seven expressed herpes simplex virus 1 (HSV-1) glycoproteins as vaccines to protect against ocular disease after primary ocular HSV-1 infection.

METHODS

Mice were vaccinated three times with equal amounts of each of seven individually expressed HSV-1 glycoproteins (gB, gC, gD, gE, gG, gH, and gI) and then ocularly challenged with McKrae, a corneal disease-producing strain of HSV-1. Viral clearance from the eye, blepharitis, keratitis, and neovascularization were determined at various times after infection.

RESULTS

Mice vaccinated with gD or gB had the best protection against eye disease. Vaccination with gI, gC, or gE produced moderate protection against eye disease. Vaccination with gG produced less protection, and vaccination with gH produced no apparent protection against eye disease.

CONCLUSIONS

These results suggest that when used as vaccines, different HSV-1 glycoproteins provide different levels of protection against HSV-1-induced eye disease. Based on comparison with the authors' previously published results, the ability of each glycoprotein to protect against eye disease correlated with the ability of the glycoprotein to induce high serum neutralizing antibody titers and killer cell activity. Results suggest that the effectiveness of these seven glycoproteins in protecting against eye disease can be ranked as follows: gD > gB > gI > (gC = gE) > gG > gH.

Keratoconus detected by videokeratography in candidates for photorefractive keratectomy

BACKGROUND

Patients with corneal shape abnormalities should be identified prior to photorefractive keratectomy (PRK). We used videokeratography screening to detect subclinical corneal abnormalities, including keratoconus, which might have been missed by conventional clinical evaluation.

METHODS

One hundred forty-six apparently normal myopic eyes (-1.00 to -7.00 diopters [D] with less than 1.50 D of cylinder) of 91 consecutive patients who were candidates for PRK were screened by videokeratography.

RESULTS

In 6 of 91 patients (7 of 146 eyes), unsuspected corneal shape abnormalities were detected by videokeratography. Two patients had definite keratoconus and three were classified as keratoconus suspects by inferior corneal steepening (Rabinowitz I-S index ranging from 1.62 to 6.20 D). One patient had early pellucid marginal degeneration.

CONCLUSIONS

Keratoconus suspects and contact lens-induced changes resembling keratoconus are present in the "normal" myopic population that presents for refractive surgery. Videokeratographic screening is the only effective means of identifying these and other corneal shape abnormalities.

Characterization of an endogenous metalloproteinase in human vitreous

The vitreous is a gel-like connective tissue that undergoes liquefaction during aging and pathological processes. We isolated and characterized a degradative enzyme from the vitreous of different species and identified it to be matrix metalloproteinase-2 (MMP-2). This enzyme was found in a latent form and may be associated with endogenous inhibitors. Vitreous isolated from both non-diabetic and diabetic patients contained MMP-2 in the same concentrations. However, the diabetic samples had an additional gelatinase activity at 92 kDa which may be associated with a compromised vasculature. These results suggest that the normal human vitreous contains an endogenous MMP and the appearance of an additional activity is associated with pathologic conditions.

Vaccine therapy for ocular herpes simplex virus (HSV) infection: periocular vaccination reduces spontaneous ocular HSV type 1 shedding in latently infected rabbits

Periocular vaccination of rabbits with preexisting herpes simplex virus type 1 (HSV-1) latent infection with recombinant HSV-2 glycoproteins B and D (gB2 and gD2) plus adjuvant significantly reduced ocular viral shedding. Rabbits were infected in both eyes with HSV-1 strain McKrae. Following HSV-1 infection and the establishment of latency (28 days postinfection), rabbits were given a periocular subconjunctival vaccination three times at 3-week intervals. Beginning 3 weeks after the final vaccination, tear films were collected daily and cultured to detect the presence of HSV-1 and determine the spontaneous HSV-1 ocular shedding rates. Periocular vaccination increased the mean HSV-1 serum neutralizing antibody titer to fivefold above that seen in mock-vaccinated latently infected rabbits. gB enzyme-linked immunosorbent assay (ELISA) antibody titers were increased approximately 8-fold, and gD ELISA antibody titers were increased 60-fold. These increases were all statistically significant (P < 0.0001). In two independent experiments, vaccination reduced the spontaneous shedding rate by approximately 2.5-fold (P < 0.0004). In addition, the percentage of eyes that never shed virus during the 6 week postvaccination test period increased threefold (20% in controls versus 60% in vaccinated animals; P < 0.007). These results show that spontaneous ocular shedding of HSV-1 in latently infected rabbits can be significantly reduced by local periocular vaccination. This is the first report in any animal model of a successful therapeutic vaccine against recurrent HSV-1 ocular shedding. These results support the concept that development of a therapeutic vaccine for ocular HSV-1 recurrence in humans is possible.

Preoperative irradiation and fluorouracil chemotherapy for locally advanced rectosigmoid carcinoma: phase I-II study

From June 1988 to July 1991, 20 patients with locally advanced rectal or rectosigmoid cancer were treated prospectively with a strategy of combining preoperative irradiation and fluorouracil chemotherapy before surgical resection. The preoperative radiation dose was 5,000 cGy, and fluorouracil chemotherapy was administered on the first and last 3 days of irradiation in an intravenous bolus dose of 500 mg/m2. In a median follow-up of 25 months, the local regional failure rate was 10%. The 3-year actuarial overall survival and disease-free survival were 92% and 82%, respectively. Twenty percent of the surgical specimens showed no residual tumor, and only 10% showed positive lymph nodes. Significant leukopenia occurred in 10% of patients. Preoperative irradiation and fluorouracil chemotherapy increased surgical downstaging and improved local regional control. The overall toxicity was acceptable. The results of this particular multimodality approach was encouraging and warrant further investigation in phase III trials.