Preoperative free access to water compared to fasting for planned cesarean under spinal anesthesia: a randomized controlled trial

BACKGROUND

Contemporary guidance for preoperative feeding allows solids up to 6 hours and clear fluids up to 2 hours before anesthesia. Clinical trial evidence to support this approach for cesarean delivery is lacking. Many medical practitioners continue to follow conservative policies of no intake from midnight to the time of surgery, especially in pregnant women.

OBJECTIVE

This study aimed to evaluate the pragmatic approach of permitting free access to water up to the call to dispatch to the operating theater vs fasting from midnight in preoperative oral intake restriction for planned cesarean delivery under spinal anesthesia on perioperative vomiting and maternal satisfaction.

STUDY DESIGN

A randomized controlled trial was conducted in the obstetrical unit of the University of Malaya Medical Centre from October 2020 to May 2022. A total of 504 participants scheduled for planned cesarean delivery were randomized: 252 undergoing preoperative free access to water up to the call to dispatch to the operating theater (intervention group) and 252 undergoing fasting from midnight (fasting arm). The primary outcomes were perioperative vomiting and maternal satisfaction. Analyses were performed using t test, Mann-Whitney U test, and chi-square test, as appropriate.

RESULTS

Of note, 9 of 252 patients (3.6%) in the intervention group and 24 of 252 patients (9.5%) in the control group had vomiting at up to 6 hours after completion of cesarean delivery (relative risk, 0.38; 95% confidence interval, 0.18-0.79; P=.007), and the maternal satisfaction scores (0-10 visual numerical rating scale) were 9 (interquartile range, 8-10) in the intervention group and 5 (interquartile range, 3-7) in the control group (P<.001). Assessed before dispatch to the operating theater, feeling of thirst was reported by 69 of 252 patients (27.4%) in the intervention group and 134 of 252 patients (53.2%) in the control group (relative risk, 0.52; 95% confidence interval, 0.41-0.65; P<.001), capillary glucose levels were 4.8±0.7 mmol/L in the intervention group and 4.9±0.8 mmol/L in the control group (P=.048), and preoperative intravenous fluid hydration was commenced in 49 of 252 patients (19.4%) in the intervention group and 76 of 252 patients (30.2%) in the control group (relative risk, 0.65; 95% confidence interval, 0.47-0.88; P=.005). In the operating theater, ketone was detected in the catheterized urine in 38 of 252 patients (15.1%) in the intervention group and 78 of 252 patients (31.0%) in the control group (relative risk, 0.49; 95% confidence interval, 0.25-0.59; P<.001), and the numbers of doses of vasopressors needed to correct hypotension were 2.3±1.7 in the intervention group and 2.7±2.2 in the control (P=.009). The recommendation rates for preoperative oral intake regimen to a friend were 95.2% (240/252) in the intervention group and 39.7% (100/252) in the control group (relative risk, 2.40; 95% confidence interval, 2.06-2.80; P<.001), in favor of free access to water. Other assessed maternal and neonatal outcomes were not different.

CONCLUSION

Compared with fasting, free access to water in planned cesarean delivery reduced perioperative vomiting and was strongly favored by women. In addition, several pre- and intraoperative secondary outcomes were improved. However, postcesarean delivery recovery and neonatal outcomes were not different.

Preliminary insight on diarylpentanoids as potential antimalarials: In silico, in vitro pLDH and in vivo zebrafish toxicity assessment

Malaria remains a major public health problem worldwide, including in Southeast Asia. Chemotherapeutic agents such as chloroquine (CQ) are effective, but problems with drug resistance and toxicity have necessitated a continuous search for new effective antimalarial agents. Here we report on a virtual screening of ∼300 diarylpentanoids and derivatives, in search of potential Plasmodium falciparum lactate dehydrogenase (PfLDH) inhibitors with acceptable drug-like properties. Several molecules with binding affinities comparable to CQ were chosen for in vitro validation of antimalarial efficacy. Among them, MS33A, MS33C and MS34C are the most promising against CQ-sensitive (3D7) with EC50 values of 1.6, 2.5 and 3.1 μM, respectively. Meanwhile, MS87 (EC50 of 1.85 μM) shown the most active against the CQ-resistant Gombak A strain, and MS33A and MS33C the most effective P. knowlesi inhibitors (EC50 of 3.6 and 5.1 μM, respectively). The in vitro cytotoxicity of selected diarylpentanoids (MS33A, MS33C, MS34C and MS87) was tested on Vero mammalian cells to evaluate parasite selectivity (SI), showing moderate to low cytotoxicity (CC50 > 82 μM). In addition, MS87 exhibited a high SI and the lowest resistance index (RI), suggesting that MS87 may exert effective parasite inhibition with low resistance potential in the CQ-resistant P. falciparum strain. Furthermore, the in vivo toxicity of the molecules on early embryonic development, the cardiovascular system, heart rate, motor activity and apoptosis were assessed in a zebrafish animal model. The overall results indicate the preliminary potential of diarylpentanoids, which need further investigation for their development as new antimalarial agents.

Kinetic analysis of cardiac dynamic 18F-Florbetapir PET in healthy volunteers and amyloidosis patients: A pilot study

Objectives

This study aimed to explore the potential of full dynamic PET kinetic analysis in assessing amyloid binding and perfusion in the cardiac region using 18F-Florbetapir PET, establishing a quantitative approach in the clinical assessment of cardiac amyloidosis disease.

Materials & methods

The distribution volume ratios (DVRs) and the relative transport rate constant (R1), were estimated by a pseudo-simplified reference tissue model (pSRTM2) and pseudo-Logan plot (pLogan plot) with kidney reference for the region of interest-based and voxel-wise-based analyses. The parametric images generated using the pSRTM2 and linear regression with spatially constrained (LRSC) algorithm were then evaluated. Semi-quantitative analyses include standardized uptake value ratios at the early phase (SUVREP, 0.5-5 min) and late phase (SUVRLP, 50-60 min) were also calculated.

Results

Ten participants [7 healthy controls (HC) and 3 cardiac amyloidosis (CA) subjects] underwent a 60-min dynamic 18F-Florbetapir PET scan. The DVRs estimated from pSRTM2 and Logan plot were significantly increased (HC vs CA; DVRpSRTM2: 0.95 ± 0.11 vs 2.77 ± 0.42, t'(2.13) = 7.39, P = 0.015; DVRLogan: 0.80 ± 0.12 vs 2.90 ± 0.55, t'(2.08) = 6.56, P = 0.020), and R1 were remarkably decreased in CA groups, as compared to HCs (HC vs CA; 1.08 ± 0.37 vs 0.56 ± 0.10, t'(7.63) = 3.38, P = 0.010). The SUVREP and SUVRLP were highly correlated to R1 (r = 0.97, P < 0.001) and DVR(r = 0.99, P < 0.001), respectively. The DVRs in the total myocardium region increased slightly as the size of FWHM increased and became stable at a Gaussian filter ≥6 mm. The secular equilibrium of SUVR was reached at around 50-min p.i. time.

Conclusion

The DVR and R1 estimated from cardiac dynamic 18F-Florbetapir PET using pSRTM with kidney pseudo-reference tissue are suggested to quantify cardiac amyloid deposition and relative perfusion, respectively, in amyloidosis patients and healthy controls. We recommend a dual-phase scan: 0.5-5 min and 50-60 min p.i. as the appropriate time window for clinically assessing cardiac amyloidosis and perfusion measurements using 18F-Florbetapir PET.

The efficacy of short acquisition time using 18F-FDG total-body PET/CT for the identification of pediatric epileptic foci

BACKGROUND

18F-FDG positron emission tomography (PET) plays a crucial part in the evaluation for pediatric epileptic patients prior to therapy. Short-term scanning holds significant importance, especially for pediatrics epileptic individuals who exhibited involuntary movements. The aim was to evaluate the effects of short acquisition time on image quality and lesion detectability in pediatric epileptic patients using total-body (TB) PET/CT. A total of 25 pediatric patients who underwent TB PET/CT using uEXPLORER scanner with an 18F-FDG administered dose of 3.7 MBq/kg and an acquisition time of 600 s were retrospectively enrolled. Short acquisition times (60 s, 150 and 300 s) were simulated by truncating PET data in list mode to reduce count density. Subjective image quality was scored on a 5-point scale. Regions of interest analysis of suspected epileptogenic zones (EZs), corresponding locations contralateral to EZs, and healthy cerebellar cortex were used to compare the semi-quantitative uptake indices of short-time images and then were compared with 600 s images. The comparison of EZs detectability based on time-dependent PET images was performed.

RESULTS

Our study demonstrated that a short acquisition time of 150 s is sufficient to maintain subjective image quality and lesion significance. Statistical analysis revealed no significant difference in subjective PET image quality between imaging at 300 s and 150 s (P > 0.05). The overall impression scores of image quality and lesion conspicuity in G60s were both greater than 3 (overall quality, 3.21 ± 0.46; lesion conspicuity, 4.08 ± 0.74). As acquisition time decreased, the changes of SUVmax and SD in the cerebellar cortex gradually increased (P < 0.01). There was no significant difference in asymmetry index (AI) difference between the groups and the AIs of EZs were > 15% in all groups. In 26 EZs of 25 patients, the lesion detection rate was still 100% when the time was reduced to 60 s.

CONCLUSIONS

This study proposed that TB PET/CT acquisition time could be reduced to 60 s with acceptable lesion detectability. Furthermore, it was suggested that a 150 s acquisition time would be sufficient to achieve diagnostic performance and image quality for children with epilepsy.

Assessing dynamic metabolic heterogeneity in prostate cancer patients via total-body [68Ga]Ga-PSMA-11 PET/CT imaging: quantitative analysis of [68Ga]Ga-PSMA-11 uptake in pathological lesions and normal organs

PURPOSE

This study aimed to quantitatively assess [68Ga]Ga-PSMA-11 uptake in pathological lesions and normal organs in prostate cancer using the total-body [68Ga]Ga-PSMA-11 PET/CT and to characterize the dynamic metabolic heterogeneity of prostate cancer.

METHODS

Dynamic total-body [68Ga]Ga-PSMA-11 PET/CT scans were performed on ten prostate cancer patients. Manual delineation of volume-of-interests (VOIs) was performed on multiple normal organs displaying high [68Ga]Ga-PSMA-11 uptake, as well as pathological lesions. Time-to-activity curves (TACs) were generated, and the four compartment models including one-tissue compartmental model (1T1k), reversible one-tissue compartmental model (1T2k), irreversible two-tissue compartment model (2T3k) and reversible two-tissue compartmental model (2T4k) were fitted to each tissue TAC. Various rate constants, including K1 (forward transport rate from plasma to the reversible compartment), k2 (reverse transport rate from the reversible compartment to plasma), k3 (tracer binding on the PSMA-receptor and its internalization), k4 (the externalization rate of the tracer) and Ki (net influx rate), were obtained. The selection of the optimal model for describing the uptake of both lesions and normal organs was determined using the Akaike information criteria (AIC). Receiver operating characteristic (ROC) curve analysis was performed to determine the cut-off values for differentiating physiological and pathological [68Ga]Ga-PSMA-11 uptake.

RESULTS

Both 1T1k and 1T2k models showed relatively high AIC values compared to the 2T3k and 2T4k models in both pathological lesions and normal organs. The kinetic behavior of pathological lesions was better described by the 2T3k model compared to the 2T4k model, while the normal organs were better described by the 2T4k model. Significant variations in kinetic metrics, such as K1, k2, and k3, and Ki, were observed among normal organs with high [68Ga]Ga-PSMA-11 uptake and pathological lesions. The high Ki value in normal organs was primarily determined by elevated K1 and low k3, rather than k2. Conversely, the high Ki value in pathological lesions, ranking second to the kidney and similar to salivary glands and spleen, was predominantly determined by the highest k3 value. Notably, k3 exhibited the highest performance in distinguishing between physiological and pathological [68Ga]Ga-PSMA-11 uptake, with an area under the curve (AUC) of 0.844 (95% CI, 0.773-0.915), sensitivity of 82.9%, and specificity of 74.1%. The k3 values showed better performance than SUVmean (AUC, 0.659), SUVmax (AUC, 0.637), and other kinetic parameter including K1 (AUC, 0.604), k2 (AUC, 0.634), and Ki (AUC, 0.651).

CONCLUSIONS

Significant discrepancies in kinetic metrics were detected between pathological lesions and normal organs, despite their shared high uptake of [68Ga]Ga-PSMA-11. Notably, the k3 value exhibits a noteworthy capability to distinguish between pathological lesions and normal organs with elevated [68Ga]Ga-PSMA-11 uptake. This discovery implies that k3 holds promise as a prospective imaging biomarker for distinguishing between pathologic and non-specific [68Ga]Ga-PSMA-11 uptake in patients with prostate cancer.

Comparison of parametric imaging and SUV imaging with [68 Ga]Ga-PSMA-11 using dynamic total-body PET/CT in prostate cancer

PURPOSE

Standardized uptake value (SUV) has been prevalently used to measure [68 Ga]Ga-PSMA-11 activity in prostate cancer, but it is susceptible to multiple factors. Parametric imaging allows for absolute quantification of tracer uptake and provides a better diagnostic accuracy that is crucial for lesion detection. However, the clinical significance of total-body parametric imaging of [68 Ga]Ga-PSMA-11 remains to be fully assessed. Therefore, the aim of our study is to delve into the diagnostic implications of total-body parametric imaging of [68 Ga]Ga-PSMA-11 PET/CT for patients with prostate cancer.

METHODS

Twenty prostate cancer patients were included and underwent a dynamic total-body [68 Ga]Ga-PSMA-11 PET/CT scan. An irreversible two-tissue compartment model (2T3k) was fitted for each tissue time-to-activity curve, and the net influx rate (Ki) was obtained. The image quality and semi-quantitative analysis of lesion-to-background ratio (LBR), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were compared between parametric images and SUV images.

RESULTS

Kinetic modeling using 2T3k demonstrated favorable model fitting in both normal organs and lesions. All of the lesions detected on SUV images (55-60 min) could be detected on Ki images. The correlation between Ki, SUVmean, and SUVmax in both normal organs and pathological lesions was found to be positive and statistically significant. Conversely, a moderate positive correlations were found between Ki and K1 (R = 0.69, P < 0.001; R = 0.61, P < 0.001) and Ki and k3 (R = 0.69, P < 0.001; R = 0.62, P < 0.001), in normal organs and pathological lesions, respectively. Visual assessment in Ki images showed less image noise and higher lesions conspicuity compared to SUV images. Ki image-derived LBR, SNR, and CBR of pathological lesions including primary tumors (PTs), lymph node metastases (LNMs) and bone metastases (BMs), exhibited remarkably higher folds (1.4-3.6 folds) compared to those derived from SUV of corresponding lesions.

CONCLUSIONS

Total-body parametric imaging of [68 Ga]Ga-PSMA-11 enhanced lesion contrast and improved lesion detectability compared to SUV images. This may potentially serve as an imaging biomarker and theranostic tool for precise diagnosis and treatment evaluation in prostate cancer patients.

The feasibility of quantitative assessment of dynamic 18F-fluorodeoxyglucose PET in Takayasu's arteritis: a pilot study

PURPOSE

PET has been demonstrated to be sensitive for detecting active inflammation in Takayasu's arteritis (TAK) patients, but semi-quantitative-based assessment may be susceptible to various biological and technical factors. Absolute quantification via dynamic PET (dPET) may provide a more reliable and quantitative assessment of TAK-active arteries. The purpose of this study was to investigate the feasibility and efficacy of dPET in quantifying TAK-active arteries compared to static PET.

MATERIALS AND METHODS

This prospective study enrolled 10 TAK-active patients (fulfilled the NIH criteria) and 5 control participants from March to October 2022. One-hour dPET scan (all TAK and control participants) and delayed static PET scan at 2-h (all TAK patients) were acquired. For 1-h static PET, summed images from 50 to 60 min of the dPET were extracted. PET parameters derived from 1- and 2-h static PET including SUV (SUV1H and SUV2H), target-to-background ratio (TBR) (TBR1H and TBR2H), net influx rate (Ki), and TBRKi extracted from dPET were obtained. The detectability of TAK-active arteries was compared among different scanning methods using the generalized estimating equation (GEE) with a logistic regression with repeated measures, and the GEE with gamma distribution and log link function was used to evaluate the different study groups or scanning methods.

RESULTS

Based on the disease states, 5 cases of TAK were classified as untreated and relapsed, respectively. The SUVmax on 2-h PET was higher than that on 1-h PET in the untreated patients (P < 0.05). However, no significant differences were observed in the median SUVmax between 1-h PET and 2-h PET in the relapsed patients (P > 0.05). The TBRKi was significantly higher than both TBR1H and TBR2H (all P < 0.001). Moreover, the detectability of TAK-active arteries by dPET-derived Ki was significantly higher than 1-h and 2-h PET (all P < 0.001). Significant differences were observed in Kimax, SUVmax-1H, TBR1H, and TBRKi among untreated, relapsed, and control groups (all P < 0.05).

CONCLUSIONS

Absolute quantitative assessment by dPET provides an improved sensitivity and detectability in both visualization and quantification of TAK-active arteries. This elucidates the clinical significance of dPET in the early detection of active inflammation and monitoring recurrence.

Improved accuracy of the biodistribution and internal radiation dosimetry of 13 N-ammonia using a total-body PET/CT scanner

BACKGROUND

Conventional short-axis PET typically utilizes multi-bed multi-pass acquisition to produce quantitative whole-body dynamic images and cannot record all the uptake information simultaneously, resulting in errors when fitting the time-activity curves (TACs) and calculating radiation doses.

PURPOSE

The aim of this study is to evaluate the 13 N-ammonia biodistribution and the internal radiation doses using a 194 cm long total-body PET/CT scanner (uEXPLORER), and make a comparison with the previous short-axis PET results.

METHODS

Ten subjects (age 40-74 years) received 13 N-NH3 injection (418.1-670.81 MBq) and were under a dynamic scan for about 60 min with using a 3-dimensional whole-body protocol. ROIs were drawn visually on 11 major organs (brain, thyroid, gallbladder, heart wall, kidneys, liver, pancreas, spleen, lungs, bone marrow, and urinary bladder content) for each subject. TACs were generated using Pmod and the absorbed radiation doses were calculated using Olinda 2.2. To compare with the conventional PET/CT, five points were sampled on uEXPLORER's TACs to mimic the result of a short-axis PET/CT (15 cm axial FOV, consisted of 9 or 10 bed positions). Then the TACs were obtained using the multi-exponential fitting method, and the residence time and radiation dose were also calculated and compared with uEXPLORER.

RESULTS

The highest absorbed organ doses were the pancreas, thyroid, spleen, heart wall, and kidneys for the male. For the female, the first five highest absorbed organ dose coefficients were the pancreas, heart wall, spleen, lungs, and kidneys. The lowest absorbed dose was found in red marrow both for male and female. The simulated short-axis PET can fit TACs well for the gradually-changed uptake organs but typically underestimated for the rapid-uptake organs during the first-10 min, resulting in errors in the calculated radiation dose.

CONCLUSION

uEXPLORER PET/CT can measure 13 N-ammonia's TACs simultaneously in all organs of the whole body, which can provide more accurate biodistribution and radiation dose estimation compared with the conventional short-axis scanners.

Improved [68Ga]Ga-PSMA-11 image qualities reconstructed by total variation regularized expectation maximization on total-body PET/CT

Background

Total variation regularized expectation maximization (TVREM) reconstruction algorithm on the image quality of gallium (68GA) prostate-specific membrane antigen-11 ([68Ga]Ga-PSMA-11) total-body positron emission tomography/computed tomography (PET/CT).

Methods

Images of a phantom with small hot sphere inserts and the total-body PET/CT scans of 51 prostate cancer patients undergoing [68Ga]Ga-PSMA-11 were reconstructed using TVREM with 5 different penalization factors between 0.09 and 0.45 and for 20-, 40-, 60-, 120-, and 300-second acquisition, respectively. As a comparison, the same data were also reconstructed using the ordered subset expectation maximization (OSEM) with 3 iterations, 20 subsets, and 300 second acquisition. The contrast recovery coefficients (CRC) and background variability (BV) of the phantom, the tumor-to-background ratios (TBR), the contrast recovery (CR) ratio, the image noise of the liver, and maximum standard uptake value (SUVmax) of the lesions were calculated to evaluate the image quality. The clinical performance of the images was evaluated by 2 radiologists with a 5-point scale (1-poor, 5-excellent).

Results

The TVREM reconstructions groups fwith 120 second acquisition and the penalization of 0.27 to 0.45 showed the best performance in terms of CR, TBR, image noise, and the gain of SUVmax compared to that obtained in the OSEM 300 second group. Even the image noise of the TVREM 120 second group with a penalization factor of 0.27 and 0.36 was comparable to the OSEM 300 second group; the lesions' SUVmax increased by 28% whereas the image noise decreased by 5% and 14%, respectively. The TVREM 120 second group with a penalization factor of 0.36 (5.00±0.00) had the highest qualitative score that equaled OSEM and TVREM for the 300 second (P>0.05) group.

Conclusions

Our study has shown the potential of the TVREM reconstruction algorithm with optimized penalization factors to achieve comparable [68Ga]Ga-PSMA-11 total-body PET/CT image quality with a shorter acquisition time, compared with the conventional OSEM reconstruction algorithm.

The feasibility of ultra-early and fast total‑body [68 Ga]Ga-FAPI-04 PET/CT scan

PURPOSE

[⁶⁸ Ga]Ga-FAPI-04 PET/CT has been widely used in oncology patients. The patients need to lie still for 20-30 min during scan after waiting for 60 min post-tracer injection in traditional [⁶⁸ Ga]Ga-FAPI-04 PET/CT scan. This is difficult for some patients who are intolerant to prolonged horizontal positioning and waiting time. Therefore, we evaluated the diagnostic value of the images obtained in ultra-early and fast scan (5-min p.i., 30-s acquisition time) by the total-body [⁶⁸ Ga]Ga-FAPI-04 PET/CT and to investigate whether they could meet the requirements of clinical diagnosis.

METHODS

Total-body [⁶⁸ Ga]Ga-FAPI-04 PET/CT was conducted in 12 patients at the Renji Hospital. Patients underwent PET with two acquisitions: 5-min p.i. and 30-s acquisition time (ultra-early and fast imaging) and 60-min p.i. and 300-s acquisition time (traditional imaging). Mean [⁶⁸ Ga]Ga-FAPI-04 injection dose was 1.85 MBq/kg.

RESULTS

Forty-four lesions were detected in 12 patients on traditional imaging. All the 44 lesions on conventional imaging could also detected by ultra-early and fast imaging. For all the 12 patients, the tumor stage did not change, as same lesions were visible for every case in both images. There was no statistically significant difference in SUVmax of lesions between ultra-early and fast imaging and traditional imaging (12.5 ± 8.7 vs 13.7 ± 8.5, P = 0.528). Background bloodpool (4.0 ± 0.6 vs 0.9 ± 0.2, P < 0.001)and liver (2.5 ± 0.7 vs 1.0 ± 0.5, P < 0.001)at traditional imaging showed a significant decrease in SUVmean compared to ultra-early and fast imaging.

CONCLUSIONS

Ultra-early and fast imaging versus traditional [⁶⁸ Ga]Ga-FAPI-04 imaging resulted in equivalent tumor detection and lesion uptake. Ultra-early and fast total-body [⁶⁸ Ga]Ga-FAPI-04 PET/CT scan could meet clinical diagnostic requirements for patients with poor tolerant to prolonged horizontal positioning and waiting time.

The Impact of Geographical Variation in Plasmodium knowlesi Apical Membrane Protein 1 (PkAMA-1) on Invasion Dynamics of P. knowlesi

Plasmodium knowlesi has emerged as an important zoonotic parasite that causes persistent symptomatic malaria in humans. The signs and symptoms of malaria are attributed to the blood stages of the parasites, which start from the invasion of erythrocytes by the blood stage merozoites. The apical membrane protein 1 (AMA-1) plays an important role in the invasion. In this study, we constructed and expressed recombinant PkAMA-1 domain II (PkAMA-1-DII) representing the predominant haplotypes from Peninsular Malaysia and Malaysian Borneo and raised specific antibodies against the recombinant proteins in rabbits. Despite the minor amino acid sequence variation, antibodies raised against haplotypes from Peninsular Malaysia and Malaysian Borneo demonstrated different invasion inhibition (46.81% and 39.45%, respectively) to P. knowlesi A1-H.1, a reference strain derived from Peninsular Malaysia. Here, we demonstrated how a minor variation in a conserved parasite protein could cast a significant impact on parasite invasion biology, suggesting a complex host-switching of P. knowlesi from different locations. This may challenge the implementation of a standardized One Health approach against the transmission of knowlesi malaria.

First total-body kinetic modeling and parametric imaging of dynamic 68Ga-FAPI-04 PET in pancreatic and gastric cancer

Background: Fibroblast activation protein inhibitor (FAPI) is an ideal diagnostic and therapeutic target in malignant tumors. However, the knowledge of kinetic modelling and parametric imaging of ⁶⁸Ga-FAPI is limited. Purpose: To explore the pharmacokinetics of ⁶⁸Ga-FAPI-04 PET/CT in pancreatic cancer and gastric cancer and to conduct parametric imaging of dynamic total-body data compared to standardized uptake value (SUV) imaging. Methods: Dynamic total-body ⁶⁸Ga-FAPI-04 PET/CT (with an AFOV of 194 cm) was performed on thirteen patients. The lesion time activity curves (TACs) were fitted by three-compartment models and multigraphical models. The kinetics parameters derived from the two-tissue reversible compartment model (2T4K) and multigraphical models were analyzed. Parametric 𝑉𝑡 imaging was generated using the 2T4K and Logan model, and their performances were evaluated compared to SUV images. Results: 2T4K had the lowest Akaike Information Criterion (AIC) value and its fitting curves matched excellently with the origin TACs. Visual assessment revealed that the 𝑉𝑡 (2T4K) images and 𝑉𝑡 (Logan with SC) images both showed less image noise and higher lesions conspicuity compared to SUV images. Objective image quality assessment demonstrated that parametric 𝑉𝑡 (2T4K) images and parametric 𝑉𝑡 (Logan with SC) images had a 5.0-fold and 5.0-fold higher average signal-to-noise ratio (SNR), and 3.6-fold and 4.1-fold higher average contrast-to-noise ratio (CNR) compared to conventional SUV images, respectively. In addition, no significant differences in SNR and CNR of pathological lesions were observed between parametric 𝑉𝑡 (2T4K) images and Parametric 𝑉𝑡 (Logan with SC) images (p all ＞0.05). Conclusion: The 2T4K model was the preferred compartment model. Total-body parametric imaging of ⁶⁸Ga-FAPI-04 PET yielded superior quantification beyond SUV with enhanced lesion contrast, which may serve as a promising imaging method for early diagnosis, to better reflect tumor characterization, or to allow evaluation of treatment response. 𝑉𝑡 (2T4K) images are comparable in image quality and superior to 𝑉𝑡 (Logan with SC) images in lesions conspicuity, however 𝑉𝑡 (Logan with SC) images presented an appealing alternative to 𝑉𝑡 (2T4K) images due to their simplicity.

Tracer-specific reference tissues selection improves detection of 18 F-FDG, 18 F-florbetapir, and 18 F-flortaucipir PET SUVR changes in Alzheimer's disease

This study sought to identify a reference tissue‐based quantification approach for improving the statistical power in detecting changes in brain glucose metabolism, amyloid, and tau deposition in Alzheimer's disease studies. A total of 794, 906, and 903 scans were included for ¹⁸F‐FDG, ¹⁸F‐florbetapir, and ¹⁸F‐flortaucipir, respectively. Positron emission tomography (PET) and T1‐weighted images of participants were collected from the Alzheimer's disease Neuroimaging Initiative database, followed by partial volume correction. The standardized uptake value ratios (SUVRs) calculated from the cerebellum gray matter, centrum semiovale, and pons were evaluated at both region of interest (ROI) and voxelwise levels. The statistical power of reference tissues in detecting longitudinal SUVR changes was assessed via paired t‐test. In cross‐sectional analysis, the impact of reference tissue‐based SUVR differences between cognitively normal and cognitively impaired groups was evaluated by effect sizes Cohen's d and two sample t‐test adjusted by age, sex, and education levels. The average ROI t values of pons were 86.62 and 38.40% higher than that of centrum semiovale and cerebellum gray matter in detecting glucose metabolism decreases, while the centrum semiovale reference tissue‐based SUVR provided higher t values for the detection of amyloid and tau deposition increases. The three reference tissues generated comparable d images for ¹⁸F‐FDG, ¹⁸F‐florbetapir, and ¹⁸F‐flortaucipir and comparable t maps for ¹⁸F‐florbetapir and ¹⁸F‐flortaucipir, but pons‐based t map showed superior performance in ¹⁸F‐FDG. In conclusion, the tracer‐specific reference tissue improved the detection of ¹⁸F‐FDG, ¹⁸F‐florbetapir, and ¹⁸F‐flortaucipir PET SUVR changes, which helps the early diagnosis, monitoring of disease progression, and therapeutic response in Alzheimer's disease.

Genetic diversity of the full length apical membrane antigen-1 of Plasmodium knowlesi clinical isolates from Peninsular Malaysia

The Plasmodium knowlesi apical membrane antigen-1 (PkAMA-1) plays an important role in the invasion of the parasite into its host erythrocyte, and it has been regarded as a potential vaccine candidate against human knowlesi malaria. This study investigates genetic diversity and natural selection of the full length PkAMA-1 of P. knowlesi clinical isolates from Peninsular Malaysia. Blood samples were collected from P. knowlesi malaria patients from Peninsular Malaysia. The PkAMA-1 gene was amplified from DNA samples using PCR, cloned into a plasmid vector and sequenced. Results showed that nucleotide diversity of the full length PkAMA-1 from Peninsular Malaysia isolates (π: 0.006) was almost similar to that of Sarawak (π: 0.005) and Sabah (π: 0.004) isolates reported in other studies. Deeper analysis revealed Domain I (π: 0.007) in the PkAMA-1 had the highest diversity as compared to Domain II (π: 0.004) and Domain III (π: 0.003). Z-test indicated negative (purifying) selection of the gene. Combined alignment analysis at the amino acid level for the Peninsular Malaysia and Sarawak PkAMA-1 sequences revealed 34 polymorphic sites. Thirty-one of these sites were dimorphic, and 3 were trimorphic. The amino acid sequences could be categorised into 31 haplotypes. In the haplotype network, PkAMA-1 from Peninsular Malaysia and Sarawak were separated into two groups.

Non-surgical treatment of knee osteoarthritis

Knee osteoarthritis is one of the most common degenerative diseases causing disability in elderly patients. Osteoarthritis is an increasing problem for ageing populations, such as that in Hong Kong. It is important for guidelines to be kept up to date with the best evidence-based osteoarthritis management practices available. The aim of this study was to review the current literature and international guidelines on non-surgical treatments for knee osteoarthritis and compared these with the current guidelines in Hong Kong, which were proposed in 2005. Internationally, exercise programmes for non-surgical management of osteoarthritis have been proven effective, and a pilot programme in Hong Kong for comprehensive non-surgical knee osteoarthritis management has been successful. Long-term studies on the effectiveness of such exercise programmes are required, to inform future changes to guidelines on osteoarthritis management.

Entamoeba histolytica: Quantitative Proteomics Analysis Reveals Putative Virulence-Associated Differentially Abundant Membrane Proteins

Entamoeba histolytica is a protozoan parasite that causes amebiasis and poses a significant health risk for populations in endemic areas. The molecular mechanisms involved in the pathogenesis and regulation of the parasite are not well characterized. We aimed to identify and quantify the differentially abundant membrane proteins by comparing the membrane proteins of virulent and avirulent variants of E. histolytica HM-1:IMSS, and to investigate the potential associations among the differentially abundant membrane proteins. We performed quantitative proteomics analysis using isobaric tags for relative and absolute quantitation labeling, in combination with two mass spectrometry instruments, that is, nano-liquid chromatography (nanoLC)-matrix-assisted laser desorption/ionization-mass spectrometry/mass spectrometry and nanoLC-electrospray ionization tandem mass spectrometry. Overall, 37 membrane proteins were found to be differentially abundant, whereby 19 and 18 membrane proteins of the virulent variant of E. histolytica increased and decreased in abundance, respectively. Proteins that were differentially abundant include Rho family GTPase, calreticulin, a 70-kDa heat shock protein, and hypothetical proteins. Analysis by Protein ANalysis THrough Evolutionary Relationships database revealed that the differentially abundant membrane proteins were mainly involved in catalytic activities (29.7%) and metabolic processes (32.4%). Differentially abundant membrane proteins that were found to be involved mainly in the catalytic activities and the metabolic processes were highlighted together with their putative roles in relation to the virulence. Further investigations should be performed to elucidate the roles of these proteins in E. histolytica pathogenesis.

Co-infections of ectoparasite species in synanthropic rodents of western Sarawak, Malaysian Borneo

Little is known regarding infestation of ectoparasites in synanthropic rodents in Sarawak, Malaysia. A total of 44 rodents from three species (Rattus rattus, Rattus tiomanicus and Sundamys muelleri) were trapped from four residential areas in western Sarawak, Malaysia, for ectoparasites screening. A total of 117 ectoparasites from three hard tick species (Ixodes granulatus, Haemaphysalis sp. 1, Haemaphysalis sp. 2), three mesostigmatid mite species (Laelaps echidninus, Laelaps sedlaceki, and Laelaps nuttalli), one trombiculid mite (chigger species), and one louse species (Hoplopleura sp.), were recovered from 32 infected rodents (72.73% infestation). Infestations by multiple ectoparasite species on the same rodent individuals were recorded in R. rattus and R. tiomanicus (28.1%, n=9) in this study, while Sundamys muelleri was only infested with L. echidninus. One R. rattus individual was co-infected with ticks, louse, and mesostigmatid mite. L. echidninus was the generalist ectoparasite species that infected all three rodent species in three of the residential areas studied. Ectoparasite species diversity was significantly different among four residential areas based on Shannon index and diversity t-test (p-value <0.05). This study provides the first record of the association of synanthropic rodents with multiple ectoparasite infections in residential areas of western Sarawak, Malaysia.

Rodent Species Distribution and Hantavirus Seroprevalence in Residential and Forested areas of Sarawak, Malaysia

Rodents belong to the order Rodentia, which consists of three families in Borneo (i.e., Muridae, Sciuridae and Hystricidae). These include rats, mice, squirrels, and porcupines. They are widespread throughout the world and considered pests that harm humans and livestock. Some rodent species are natural reservoirs of hantaviruses (Family: Bunyaviridae) that can cause zoonotic diseases in humans. Although hantavirus seropositive human sera were reported in Peninsular Malaysia in the early 1980s, information on their infection in rodent species in Malaysia is still lacking. The rodent populations in residential and forested areas in Sarawak were sampled. A total of 108 individuals from 15 species of rodents were collected in residential (n = 44) and forested ( n = 64) areas. The species diversity of rodents in forested areas was significantly higher (H = 2.2342) compared to rodents in residential areas (H = 0.64715) (p < 0.001 of Zar-t test based on the Shannon index). Rattus rattus and Sundamys muelleri were present at high frequencies in both localities. An enzyme-linked immunosorbent assay (ELISA) showed that hantavirus-targeting antibodies were absent from 53 tested serum samples. This is the first report of hantavirus seroprevalence surveillance in rodent populations in Sarawak, East Malaysia. The results suggested that hantavirus was not circulating in the studied rodent populations in Sarawak, or it was otherwise at a low prevalence that is below the detection threshold. It is important to remain vigilant because of the zoonotic potential of this virus and its severe disease outcome. Further studies, such as molecular detection of viral genetic materials, are needed to fully assess the risk of hantavirus infection in rodents and humans in this region of Malaysia.

Use of activated carbon as a support medium for H2S biofiltration and effect of bacterial immobilization on available pore surface

The use of support media for the immobilization of microorganisms is widely known to provide a surface for microbial growth and a shelter that protects the microorganisms from inhibitory compounds. In this study, activated carbon is used as a support medium for the immobilization of microorganisms enriched from municipal sewage activated sludge to remove gas-phase hydrogen sulfide (H2S), a major odorous component of waste gas from sewage treatment plants. A series of designed experiments is used to examine the effect on bacteria-immobilized activated carbon (termed "biocarbon") due to physical adsorption, chemical reaction, and microbial degradation in the overall removal of H2S. H2S breakthrough tests are conducted with various samples, including microbe-immobilized carbon and Teflon discs, salts-medium-washed carbon, and ultra-pure water-washed carbon. The results show a higher removal capacity for the microbe-immobilized activated carbon compared with the activated carbon control in a batch biofilter column. The increase in removal capacity is attributed to the role played by the immobilized microorganisms in metabolizing adsorbed sulfur and sulfur compounds on the biocarbon, hence releasing the adsorption sites for further H2S uptake. The advantage for activated carbon serving as the support medium is to adsorb a high initial concentration of substrate and progressively release this for microbial degradation, hence acting as a buffer for the microorganisms. Results obtained from surface area and pore size distribution analyses of the biocarbon show a correlation between the available surface area and pore volume with the extent of microbial immobilization and H2S uptake. The depletion of surface area and pore volume is seen as one of the factors which cause the onset of column breakthrough. Microbial growth retardation is due to the accumulation of metabolic products (i.e., sulfuric acid); and a lack of water and nutrient salts in the batch biofilter are other possible causes of column breakthrough.

Volatile organic compound adsorption in a gas-solid fluidized bed

Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas concentration. Concentrations up to 220 ppm for methanol and 75 ppm for isobutane were prepared using this method.

Removal of odorous sulphur-containing gases by a new isolate from activated sludge

Biological treatment of odorous sulphur-containing compounds is attracting attention due to its benign eco-friendliness, energy-savings and low operating costs. As the biological treatment efficiency of dimethylsulphide (DMS) reported was often low and variable, selection of useful DMS-degrading microorganisms is of importance for the enhancement of the biological deodorizing process. This paper reports the successful isolation of a DMS-degrading bacterium from activated sludge, using the enrichment isolation technique. The isolate was identified by 16S rRNA gene sequencing, and found to belong to the alpha group of Proteobacteria, with an identity of 99.4% and 99.1% to the 16S rRNA gene sequences of Afipia felis and Pseudomonas carboxydohydrogena, respectively. The isolate was able to metabolize DMS as well as hydrogen sulphide (H2S). A batch experiment was performed to assess the removal characteristics of DMS by the isolate. The results showed that over half of DMS could be removed by the isolate in 3 hours when the initial DMS amount was approximately 10 micromol and 25 micromol. Removal of H2S by the isolate was evaluated by a continuous test in a 2-L gas-bubbling bottle. Although part of the H2S removal by the mineral medium itself was observed in the control test, the majority of H2S removal was believed to be attributed to the metabolic activity of the isolate. In conclusion, the isolate might be potentially useful for the enhancement of the biological deodorizing processes.

Batch experiment on H2S degradation by bacteria immobilised on activated carbons

Biological treatments of odorous compounds, as compared to chemical or physical technologies, are in general ecologically and environmentally favourable. However, there are some inefficiencies relative to the media used in biofiltration processes, such as the need for an adequate residence time; the limited lifetime, and pore blockage of media, which at present render the technology economically non-viable. The aim of the study is to develop novel active media to be used in performance-enhanced biofiltration processes, by achieving an optimum balance and combination of the media adsorption capacity with the biodegradation of H2S through the bacteria immobilised on the media. An enrichment culture was obtained from activated sludges in order to metabolise thiosulphate. Batch-wise experiments were conducted to optimise the bacteria immobilisation on activated carbon, so as to develop a novel "biocarbon". Biofilm was mostly developed through culturing the bacteria with the presence of carbons in mineral media. SEM and BET tests of the carbon along with the culturing process were used to identify, respectively, the biofilm development and biocarbon porosity. Breakthrough tests evaluated the biocarbon performance with varying gas resistance time, inlet H2S concentration, and type of support materials. Fundamental issues were discussed, including type of support material, mode of bacteria immobilisation, pore blockages, and biodegradation kinetics, etc. This batch-wise study provides a basis for our future research on optimisation of the biofiltration process using a bio-trickling reactor.

Root and canal morphology of Thai mandibular molars

AIM

To investigate the root and canal morphology of 351 mandibular permanent molars collected from an indigenous Thai population.

METHODOLOGY

The cleaned teeth were accessed, the pulp dissolved by sodium hypochlorite under ultrasonication and the pulp system injected with Indian ink. The teeth were rendered clear by demineralization and immersion in methyl salicylate. The following observations were made: (i) number of roots and their morphology; (ii) number of root canals per tooth; (iii) number of root canals per root; (iv) root canal configuration in each root using Vertucci's classification, with additional modifications; and (v) presence and location of lateral canals and intercanal communications.

RESULTS

Of 118 mandibular first molars, 13% had a third disto-lingual root. In three-rooted teeth, 80% of the main distal roots and 100% of the disto-lingual roots had type 1 canal systems. Of 60 mandibular second molars, 10% had C-shaped roots, the majority of which had type 1 (33%) or type IV (33%) canal systems. Of 173 third molars, 68% had two separate roots, 20% had fused roots and 11% had a single C-shaped root; the majority had two canals (61%).

CONCLUSIONS

This study suggests that Thai molars exhibit features of both Caucasian and Chinese teeth.

Root and canal morphology of Burmese maxillary molars

AIM

To investigate the root and canal morphology of Burmese maxillary molars using a canal staining and tooth clearing technique.

METHODOLOGY

Maxillary molars (239) were collected from indigenous Burmese patients and designated; first (90), second (77), third (72) molars. Following pulp tissue removal and canal system staining with Indian ink, the teeth were decalcified with 10% nitric acid, dehydrated and cleared with methyl salicylate. The following features were evaluated: (i) number of roots and morphology; (ii) number of canals per root: (iii) root canal configuration (Vertucci's classification); (iv) number of apical foramina per root; (v) number and location of lateral canals; and (vi) the presence of intercanal communications.

RESULTS

All first and second molars had three separate roots, whilst third molars had one of five different root forms, of which three separate (25%) or fused (31%) roots were most prevalent. The majority of palatal (100%) and disto-buccal (96%) roots possessed one canal (type I). The prevalence of mesio-buccal roots with two canals decreased from first to third molars (68%, 49%, 39%, respectively); type II (two orifices, one apical foramen) and IV (two orifices, two apical foramina) configurations were the most common. Single/fused rooted third molars had a range of number and type of canals. Most roots in all molars had one apical foramen, those with four apical foramina were confined to third molars. Intercanal communications were most prevalent in mesio-buccal roots and two/three fused rooted third molars. Lateral canals were most prevalent in the apical third of the roots of all molars.

CONCLUSIONS

The mesio-buccal roots of Burmese maxillary molars possessed a variety of canal system types. Over 50% of the first and second molars had a second mesio-buccal canal, of which over 20% had intercanal communications. The palatal and disto-buccal canals mainly had type I canals. Lateral canals were equally prevalent in all tooth types but were most common in the apical third.

A new in vitro model for the study of microbial microleakage around dental restorations: a preliminary qualitative evaluation

AIM

The aim of this study was to develop an in vitro model to replicate microbial microleakage at a tooth/ restoration interface using a constant depth film fermentor (CDFF).

METHODOLOGY

Amalgam restorations were placed in machined bovine dentine cylinders and sealed externally with varnish, leaving a 1-mm perimeter exposed around the tooth/restoration interface. The dentine cylinders were housed in a CDFF and 300-microm thick microcosm dental plaques were grown over their exposed surfaces. The biofilms were maintained with a mucin-containing artificial saliva for up to 8 weeks. Cylinders were aseptically removed from the CDFF (at 1, 2, 4, & 8 weeks) and surface-decontaminated with validated protocols prior to splitting and sampling of apposing amalgam and dentine surfaces. Scanning electron microscopy (SEM) was used to ascertain the position and structure of the bacterial aggregates. Bacterial viability was determined by vital staining of the bacteria in situ.

RESULTS

At all sampling times, SEM showed cocci, rods and filaments on both amalgam and dentine surfaces; some originated as cascades from the surface biofilm and extended into the tooth/restoration microspace. Vital staining showed the majority of bacteria from both dentine and amalgam surfaces to be viable.

CONCLUSION

This preliminary investigation showed that the CDFF may be a valuable tool for the in vitro study of the dynamics of microbial microleakage around dental restorations.

Root and canal morphology of Burmese mandibular molars

AIM

To study the root canal morphology of Burmese mandibular molars using a canal staining and tooth clearing technique.

METHODOLOGY

Mandibular molars (331) were collected from indigenous Burmese patients and designated; first (139), second (134), third (58) molars. Following pulp tissue removal and staining of the canal systems with Indian ink, the teeth were decalcified and rendered clear with methyl salicylate. Under magnification (x3), the following features were evaluated: (i) root number and morphology, (ii) number of canals per root, (iii) root canal configuration (Vertucci's classification), (iv) number of apical foramina per root, (v) number and location of lateral canals and (vi) the presence of intercanal communications.

RESULTS

Most of the mandibular molars had two separate roots (90% in first molars, 58% in second molars, 53% in third molars) and three-rooted teeth were (10%) confined to first molars. C-shaped roots occurred in 22.4% of mandibular second molars and a further 14.9% had two fused roots. The majority (81-100%) of conical distal roots possessed a simple type I (single canal) configuration. Whilst the canal system of mesial roots was more complex: 52-85% contained two canals, of which type II (two orifices, one foramen) and type IV (two separate canals) were the most prevalent. A broad range of 6.5-70% had intercanal communications. Fused/single-rooted molars had a wide variety of canal system types but intercanal communications were rare except in C-shaped roots (33%) of second molars. The majority of roots of all molars contained one or two apical foramina (91-96%) and the apical third had the highest prevalence of lateral canals.

CONCLUSIONS

There was a high prevalence of three-rooted mandibular first molars and C-shaped roots/canals in mandibular second molars from a Burmese population. Conical roots tend to have simple canal systems, whilst flatter/broader roots have more complex canal systems.

A novel application of NMR microscopy: measurement of water diffusion inside bioadhesive bonds

The self-diffusion coefficient of water (D) inside bioadhesive bonds formed by dry and prehydrated hydrophilic matrices has been spatially resolved using nuclear magnetic resonance (NMR) microscopy. One-dimensional profiles showing the variation of D inside bioadhesive bonds were calculated from nine diffusion-weighted profiles obtained immediately after bond formation and every 5 min for 30 min. The resulting data indicated that the hydration state of a hydrophilic matrix can significantly and dramatically influence the dynamics of water movement inside a bioadhesive bond.

Some factors affecting the concentration of available chlorine in commercial sources of sodium hypochlorite

AIMS

To evaluate the availability, effect of storage, dilution and heating on some commercial sources of sodium hypochlorite (NaOCl).

METHODOLOGY

All pharmacies in a Regional Health Authority were telephone surveyed to establish the proprietary and nonproprietary NaOCl products available, their cost and concentration. Ninety-six freshly produced bottles of a commercially available thin household bleach (J. Sainsbury's) were randomly stored in four different modes (full 1 L bottles in dark at room temperature, half-empty 1 L bottles under the same conditions, full 200 mL bottles under the same conditions, full 200 mL bottles stored at 37 degrees C) up to 6 months. The available chlorine in the bleach solutions was evaluated at specific time intervals (0, 1, 2 weeks, 1, 2, 3, 4, 6 months) using iodometric titration. Four brands of commercially available bleaches (J. Sainsbury's Thin Household Bleach, Tesco's Value Bleach, Tesco's Red Label Bleach, Safeway's Savers Bleach) were diluted (by 1 : 1, 1 : 2 or 1 : 3 dilution factors) and samples taken from each dilution for titration to test predictability. NaOCl solutions (5% w/w) were heated in covered or uncovered beakers up to 60-85 degrees C. Samples were taken from each beaker at time 0 and each h up to 4 h, for titration.

RESULTS

Of the 116 pharmacies, 33% could supply a proprietary product and 53% a nonproprietary product. In all, 78% were able to supply a NaOCl product. There was no significant difference (P < 0.05) in available chlorine at baseline between the different modes of storage. After storage at room temperature for 6 months, there were no significant differences (3% of original; P > 0.05) between the different modes of storage. When the storage temperature was 37 degrees C, however, there was a significant difference (38% of original; P < 0.01) at 6 months. Comparison of baseline with the concentrations of available chlorine at 6 months showed significant differences (P < 0.01) for all conditions. The available chlorine concentration in four brands of 'thin' supermarket bleaches could be predictably reduced according to the dilution factor. When 5% NaOCl was heated to 60-85 degrees C for up to 4 h, the available chlorine was increased to 6% in covered solutions and 9% in uncovered solutions.

CONCLUSIONS

Both proprietary and nonproprietary solutions of NaOCl should be relatively easily obtainable in the UK. Stored under appropriate conditions, commercially available thin bleaches and nonproprietary solutions of NaOCl may be diluted to obtain predictable concentrations. Heating solutions of NaOCl may cause unpredictable changes to the concentration, depending upon conditions.

Effect of exposing dentine to sodium hypochlorite and calcium hydroxide on its flexural strength and elastic modulus

AIM

The aim of this study was to evaluate the effect of sodium hypochlorite (NaOCl) solutions (3%, 5%) and saturated calcium hydroxide (Ca(OH)2) solution, individually and consecutively, on the flexural strength and modulus of elasticity of standardized dentine bars.

METHODOLOGY

Standardized plano-parallel dentine bars (n = 121) were divided into five test groups and one control group. The control group 1 consisted of dentine bars, stored in normal saline until testing. The dentine bars in the five test groups were treated by exposure to the following solutions; group 2--3% NaOCl, 2 h; group 3--5% NaOCl, 2 h; group 4--saturated Ca(OH)2 solution, 1 week; group 5--3% NaOCl, 2 h and then saturated Ca(OH)2 solution 1 week; group 6--5% NaOCl, 2 h and then saturated Ca(OH)2 solution 1 week. The dentine bars were then loaded to failure in a three-point bend test.

RESULTS

The data revealed a significant (P < 0.001) decrease in the modulus of elasticity and flexural strength of the dentine bars treated with 3% and 5% NaOCl. There was no significant difference in the flexural strength and the modulus of elasticity between the 3% and 5% NaOCl groups. Exposure to Ca(OH)2 significantly (P < 0.001) reduced the flexural strength but had no significant effect on the modulus of elasticity. The groups treated with sodium hypochlorite followed by calcium hydroxide did not have moduli of elasticity and flexural strengths that were significantly different from those treated only with sodium hypochlorite.

CONCLUSIONS

NaOCl (3 & 5%) reduced the modulus of elasticity and flexural strength of dentine. Saturated Ca(OH)2 reduced the flexural strength of dentine but not the modulus of elasticity. Sequential use of NaOCl and Ca(OH)2 has no additional weakening effect.

Effect of sodium hypochlorite on mechanical properties of dentine and tooth surface strain

AIM

The aim of this study was to test the null hypothesis that sodium hypochlorite irrigation of root canals does not alter the properties of dentine and contribute to the weakening of root-treated teeth.

METHODOLOGY

The effect of two concentrations (0.5%, 5.25%) of sodium hypochlorite (NaOCl) and saline on (i) the elastic modulus and flexural strength of machined dentine bars, and (ii) changes in strain of 'whole' extracted human teeth were evaluated. One hundred standardized plano-parallel dentine bars (> 11.7 x 0.8 x 0.8 mm) were randomly divided into the three groups, immersed for 2 h in the respective solutions and then subjected to a three-point bend test. Changes in strain of each of 10 teeth on cyclical nondestructive occlusal loading were measured using electrical resistance strain gauges bonded to the cervical aspects. Each tooth had its crown and enamel reduced and root canal prepared. These were irrigated sequentially in a series of four separate, 30-minute regimes; initial-saline, 0.5% NaOCl, 5.25% NaOCl and final-saline. The changes in strains after each irrigation regime were compared.

RESULTS

There was a significant decrease in elastic modulus of the dentine bars immersed in 5.25% NaOCl compared with the saline group (P < 0.01). There was also a significant decrease in flexural strength of the dentine bars in the 5.25% NaOCl group compared to both the saline and 0.5% NaOCl groups (P < 0.01). The strain data from the nondestructive tooth loading tests revealed significant increases in tensile strain between the initial-saline and the final-saline stages (P < 0.01). Significant increases in compressive strains were also found between initial-saline and 5.25% NaOCl; and between 0.5% NaOCl and 5.25% NaOCl stages (P < 0.01).

CONCLUSIONS

The null hypothesis was rejected, 5.25% NaOCl reduced the elastic modulus and flexural strength of dentine. Irrigation of root canals of single, mature rooted premolars with 5.25% NaOCl affected their properties sufficiently to alter their strain characteristics when no enamel was present.

Circulating immune complexes of xanthine oxidase in normal subjects

An antigen-specific enzyme-linked immunosorbent assay (ELISA) was developed to detect immune complexes of xanthine oxidase (XODIC), and applied to assay serum XODIC in normal subjects. It was found that XODIC of both IgM and IgG isotypes could be detected in all the 85 sera tested. XODIC levels as a percentage of total xanthine oxidase antibody (XODAb) in the free and bound forms were mostly less than 20%, and there was also significant correlation in XODIC and XODAb levels for both IgM and IgG isotypes. The implications of these findings are discussed.

Characterization of a trifluoroethanol-induced partially folded state of alpha-lactalbumin

The protein alpha-lactalbumin exists in a partially folded molten globule state at pH 2.0, the A state. This state is believed to be compact, possessing a similar amount of secondary structure to the native state but having a flexible tertiary structure comprised mainly of non-specific hydrophobic clustering of residues. Addition of trifluoroethanol (TFE) to bovine, human and guinea pig alpha-lactalbumin at pH 2.0 has been found in each case to induce a conformational transition in the A state as monitored by circular dichroism, nuclear magnetic resonance chemical shifts, and 1-anilinonaphthalene-8-sulphonate binding. The mid-point of this transition is near 15% (v/v) TFE and is effectively complete by 50% (v/v) TFE at 315 K. Far ultraviolet circular dichroism ellipticities at 208 nm and 220 nm, usually taken as a measure of the degree of helical character, are substantially more negative in the TFE state than in the A state. Furthermore, backbone amide protons protected from solvent exchange in the A state are generally at least as strongly protected in the TFE state; patterns of protection appear similar in the two states and include at least part of both the B and C alpha-helices. One major difference from the A state is nevertheless evident: the ability to bind the fluorescent probe 1-anilinonaphthalene-8-sulphonate, characteristic of molten globule states, is lost in the TFE state. Like the A state, the TFE state of alpha-lactalbumin shows little chemical shift dispersion of side-chain resonances. Extensive line broadening in the nuclear magnetic resonance spectra, characteristic of slow conformational averaging in the A state, is, however, much reduced in the TFE state. The line narrowing observed in the TFE state has made it possible to obtain directly sequence-specific assignments for about 25% of the 123 residues of bovine alpha-lactalbumin in 50% (v/v) TFE. Two helices are amongst regions of structure so far identified from short-range backbone nuclear Overhauser enhancement (NOE) connectivities in two-dimensional spectra of the TFE state. One of the helices (residues 86 to 96) corresponds to the C-helix in the native structure. The other (residues 35 to 41) corresponds, however, to a region of the sequence that is not helical in the native state. The partially folded state of alpha-lactalbumin formed in TFE, therefore, supports both native and non-native secondary structure in the absence of persistent long-range tertiary structure.

HTLV-1-associated cutaneous disease: a clinicopathological and molecular study of patients from the U.K

The clinicopathological features of eight patients with cutaneous disease associated with HTLV-1 infection are reviewed. All were U.K. residents of West Indian extraction, and two are currently alive. Disease remained confined to the skin in two patients. Five patients with a cutaneous prodromal phase developed leukaemia after a median duration of 124 months (3 months-21 years), and in one of these combination chemotherapy produced a sustained clinical remission for 20 months. Two patients developed cutaneous disease after remission of their leukaemia. Cutaneous lesions were heterogeneous and included localized papules, a generalized papulonodular eruption, diffuse and localized erythematous plaques, pompholyx-like lesions on the palms and soles, and tumours. The histology of the skin lesions was also variable, and consisted of a heavy dermal infiltrate with lymphocytes, histiocytes, plasma cells, eosinophils and cytologically atypical mononuclear cells. Epidermotropism was present in biopsies from five patients. Tumour cells with large, densely staining, pleomorphic nuclei, arranged in rows between collagen bundles, were present in the majority of cases. In one patient the infiltrate also consisted of epithelioid cells and multinucleated giant cells. Six cases were classified histologically as pleomorphic T-cell lymphoma, and two as cerebriform or mycosis fungoides type. Molecular studies revealed a clonal T-cell population associated with monoclonal integration of HTLV-1 provirus in tissue DNA from six patients. In two patients HTLV-1 integration was established retrospectively using enzymatic in vitro amplification of a specific HTLV-1 po1 gene sequence in DNA extracted from paraffin-embedded sections. This study indicates that the clinical and pathological features of HTLV-1-associated cutaneous disease are diverse. Patients may have disease confined to the skin for prolonged periods, either at presentation or following clinical relapse--cutaneous adult T-cell lymphoma. Molecular techniques allow distinction from other types of cutaneous T-cell lymphoma, and provide an opportunity for retrospective studies of archival material.

Coexistent cutaneous T-cell lymphoma and B-cell chronic lymphocytic leukaemia

Three patients with cutaneous T-cell lymphoma (CTCL) are reported who had concurrent B-cell chronic lymphocytic leukaemia (B-CLL). The separate lineage and clonal nature of the individual lymphoid malignancies were confirmed by gene-rearrangement analysis. The chronology of the illnesses did not support the hypothesis that CTCL predisposes to the development of B-cell proliferative disorders. There was no clear association with immunosuppressive therapy, and HTLV-1 studies were negative in all patients. Consequently, we speculate that a lymphoid stem cell defect, which may lead to the development of either aberrant B- or T-cell clones, may be responsible for such cases of dual lymphoid neoplasia.

An epidemiological survey of respiratory morbidity among granite quarry workers in Singapore: radiological abnormalities

This report presents baseline findings from the first of a series of epidemiological studies to evaluate inter alia the effects of control measures introduced in 1972-79 to reduce dust exposure in all quarries in Singapore. The prevalence of radiological abnormalities among 219 currently employed quarry workers were estimated according to a number of parameters of dust exposure. Large-sized chest x-ray films were read, independently and in random order, by a panel of three experienced readers, who were "blinded" to the personal particulars and exposure of the subjects, using standard chest x-ray films to record opacities according to the International Standard Classification of Radiographs of Pneumoconioses. Silicosis as defined by radiological small opacities (both rounded and irregular) of profusion 1/1 or greater as read by at least two readers were noted in 11 subjects. The prevalence of silicosis was 12.5% in highly exposed drilling and crushing workers, and 0.8% in maintenance and transportation workers with low level exposure to granite dust. Among those who were first exposed to granite dust after 1979, no cases of silicosis were noted in any quarry worker. It is concluded that reduction in dust exposure since 1979 has so far been successful in producing nil or negligible risks of silicosis among active quarry workers over ten years, but further follow-up studies are needed.

An epidemiological survey of respiratory morbidity among granite quarry workers in Singapore: chronic bronchitis and lung function impairment

Respiratory symptoms of chronic bronchitis and measurements of lung function were studied in an epidemiological survey of the total population of workers currently employed in granite quarries in Singapore. There were 85 rock drilling and crushing workers with current exposure in high levels of silica dust. Their respiratory parameters were studied with reference to an internal comparison group of 154 quarry maintenance and transport workers with low dust exposure, and an external comparison group of 148 Telecoms postal delivery workers with no granite dust exposure. The highly exposed workers showed greater prevalences of chronic cough and phlegm, a mean reduction of 5% in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). The increased respiratory morbidity were independent of other factors such as age and smoking. Similar results were also noted after excluding those with silicosis (defined radiologically as profusion greater than 1/1 as read by at least two of three readers). This study strongly indicates a demonstrable risk of "occupational" bronchitis (mucus hypersecretion) and obstructive and restrictive lung function impairment, apart from the "classical" risk of silicosis. Measures taken to protect the health of workers exposed to silica dust should also be based on considerations taken to protect against the risk of these respiratory disorders as well.

A study of silica nephrotoxicity in exposed silicotic and non-silicotic workers

The possible human nephrotoxicity of silica has often been suggested by previous anecdotal reports and uncontrolled clinical studies of silicotic patients. Urinary excretions of albumin, alpha-1-microglobulin (AMG), and beta-N-acetyl-glucosaminidase (NAG) were measured in 33 male workers exposed to silica (mean duration of employment 16 years) and 19 male age matched non-exposed subjects with no history of primary or secondary renal diseases. Significantly higher urinary excretions of albumin and AMG were found in the workers exposed to silica. Silicotic subjects (n = 7) also had significantly high excretions of albumin, AMG, and NAG. All but one of the silicotic patients had ceased exposure from three to 17 years before the study. Our findings suggest that prolonged exposure to silica is associated with chronic irreversible nephrotoxicity in exposed workers.

Male endocrine functions in workers with moderate exposure to lead

Evidence for the effect of occupational exposure to lead on the male endocrine system is conflicting. This study evaluated the primary (testicular) and secondary (hypothalamo pituitary testicular) effects of exposure to lead in 122 current lead workers and 49 non-exposed workers. The mean current blood lead concentration was 35.2 (range 9.6-77.4) micrograms/dl in the exposed workers, and 8.3 (range 2.6-14.8) micrograms/dl in the non-exposed workers. Concentrations of plasma luteinising hormone (LH) and follicle stimulating hormone (FSH) were both significantly higher in the exposed workers, but testosterone (T) was not significantly different between the two groups. In older exposed workers, however (greater than or equal to 40 years), plasma T concentrations were significantly lower, but LH and FSH concentrations were not significantly different. Compared with non-exposed workers, those exposed for less than 10 years had significantly raised LH and FSH and normal T concentrations whereas those exposed for 10 or more years had significantly lower T, and normal LH and FSH concentrations. The concentrations of LH and FSH showed a moderate increase in relation to blood lead concentrations in the range of 10 micrograms/dl to 40 micrograms/dl and thereafter reached a plateau or declined. No apparent trend for plasma T concentrations occurred. No significant difference in prolactin (PRL) concentration was noted. It is concluded that moderate exposure to lead was associated in dose related fashion with small but measurable changes in male endocrine functions that reflected both primary and secondary effects of lead on the testes and the hypothalamo pituitary testicular axis.

Pulmonary effects of polyvinyl chloride dust exposure on compounding workers

Spirometry, chest radiography, environmental measurements, and a questionnaire on respiratory symptoms were used to evaluate the effects of exposure to polyvinyl chloride (PVC) dust on 171 Chinese and Malay PVC compounding workers in comparison with an unexposed reference group. Workers with high cumulative PVC dust exposure had a lower forced expiratory volume in 1 s and forced vital capacity, and a higher prevalence of radiological profusion of small opacities. Wheezing or chest tightness was also significantly more frequent in this group. Unlike previous studies, the PVC compounding workers in this study were exposed to only negligible amounts, if any, of vinyl chloride monomer or thermal degradation products of PVC such as hydrogen chloride, phosgene, or chlorine. The conclusion was drawn that a low grade of pneumoconiosis and a small degree of lung function impairment is associated with PVC dust exposure. Reversible airways obstruction is also likely and warrants further investigation.

Human xanthine oxidase antibody levels: variation between males and females in Chinese and Europeans

Levels of antibody specific for Xanthine oxidase (XODAb) of the immunoglobulin classes IgG, IgM and IgA have been determined in the sera of blood donors of Chinese and European ethnic origin by immunoassay. No significant differences were found between the two ethnic groups. Significant differences were found in the distribution, of XODAb IgM levels between Chinese males and females and European males and females (chi 2 = 8.262, P = 0.025; chi 2 = 9.423, P = less than 0.001). Since the age range of the female blood donors is 16-49 years, it was postulated that the higher IgM XODAb levels in the females was the result of autoimmunisation by endothelial Xanthine oxidase during menstruation. A group of post-menopausal women showed significantly lower IgM XODAb levels compared to the blood donors (chi 2 = 31.748, P = less than 0.0005). IgM levels in a group of older men were also significantly lower (chi 2 = 3.895, P = less than 0.05) but the difference was much less marked. Unlike the younger males and females there was no significant difference in the distribution of XODAb IgM levels between older males and females. The results seem to support the hypothesis of menstrual auto-immunisation.

Enzyme-linked immunosorbent assay for determination of antibodies to xanthine oxidase

An enzyme-linked immunosorbent assay (ELISA) was developed to detect IgG, IgA and IgM antibodies to xanthine oxidase. The method used xanthine oxidase to coat sample wells on microtitre plates. The anti-xanthine oxidase concentrations were determined by reference to standard curves constructed by coating plates with anti-IgG, anti-IgA and anti-IgM to capture antibodies of different classes in standard human serum. The standard curves for IgG, IgA and IgM had a working range of 0 to about 60 ng/ml, and all results with commercial quality control serum fell within expected ranges. The coefficients of variation (CV) for within-batch precision (n = 30) and between-batch precision (n = 20) for IgG and IgM were about 9% and 12% respectively. The detection limit was 2 ng/ml. The ELISA was applied to assay serum samples of 110 Chinese and 110 European healthy subjects. A positively-skewed distribution in their anti-xanthine oxidase IgG and IgM levels was observed.

The other side of the corneal endothelium

New high-magnification biomicroscopes, the specular microscope and now the in-tandem confocal microscope, provide new images of the corneal endothelium in vivo. These are not always easy to interpret, and correlation with the morphology of the endothelium as seen in dead, fixed specimens is necessary. One such image is of the anterior surface with the confocal microscope. It exhibits a mosaic of hexagonal cells. This surface has not been specifically investigated previously in fixed preparations and the in vivo appearance does not correlate with the structure deduced from transmission electron micrographs. These indicate that the bases of endothelial cells are in the form of thin processes that would not present an image of clearly defined cell outlines. Therefore, the anterior surface of corneal endothelium stripped from ox and human corneas has been examined with the scanning electron microscope. It was found that the basal cell membranes extend processes to neighbouring cells and that some of these seem to unite. The possibility that these findings are artefactual has been examined by comparing them with published transmission and scanning electron micrographs, and it has been concluded that the processes of the basal cell membranes are real.

Effect of preservation on the elasticity of human aortic valve homografts

The elastic properties of preserved human aortic homografts after different storage times in antibiotic-nutrient medium solution have been measured. There was a definite loss of elasticity within nine months leading to a rapid decrease after a year of preservation. It is likely that satisfactory valve function depends on its elasticity, and these studies indicate that aortic valves which have been exposed to antibiotic media for more than nine months should not be used in valve replacement surgery.