Integrin α10β1-selected mesenchymal stem cells reduced hypercoagulopathy in a porcine model of acute respiratory distress syndrome

Mesenchymal stem cells (MSCs) have been studied for their potential benefits in treating acute respiratory distress syndrome (ARDS) and have reported mild effects when trialed within human clinical trials. MSCs have been investigated in preclinical models with efficacy when administered at the time of lung injury. Human integrin α10β1-selected adipose tissue-derived MSCs (integrin α10β1-MSCs) have shown immunomodulatory and regenerative effects in various disease models. We hypothesized that integrin α10β1 selected-MSCs can be used to treat a sepsis-induced ARDS in a porcine model when administering cells after established injury rather than simultaneously. This was hypothesized to reflect a clinical picture of treatment with MSCs in human ARDS. 12 pigs were randomized to the treated or placebo-controlled group prior to the induction of mild to moderate ARDS via lipopolysaccharide administration. The treated group received 5 × 106 cells/kg integrin α10β1-selected MSCs and both groups were followed for 12 h. ARDS was confirmed with blood gases and retrospectively with histological changes. After intervention, the treated group showed decreased need for inotropic support, fewer signs of histopathological lung injury including less alveolar wall thickening and reduction of the hypercoagulative disease state. The MSC treatment was not associated with adverse events over the monitoring period. This provides new opportunities to investigate integrin α10β1-selected MSCs as a treatment for a disease which does not yet have any definitive therapeutic options.

Development of acoustically isolated extracellular plasma vesicles for biomarker discovery in allogeneic hematopoietic stem cell transplantation

Background

Infection and graft-versus-host disease (GvHD) are the major causes for mortality and morbidity of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Plasma-derived extracellular vesicles (EVs) contain disease-related proteins, DNAs and RNAs, and have recently been suggested as potential biomarker candidates for transplantation complications. However, EV isolation from small plasma volumes in clinical biomarker studies using conventional methods is challenging. We therefore investigated if EVs isolated by novel automated acoustic trapping could be developed as potential biomarkers for allo-HSCT complications by performing a clinical proof-of-principle study.

Results

Plasma samples were collected from twenty consecutive patients with high-risk/relapsed hematologic malignancies undergoing allo-HSCT before transplantation and post-transplant up to 12 weeks. EVs were isolated from small plasma sample volumes (150 μl) by an automated, acoustofluidic-based particle trapping device, which utilizes a local λ/2 ultrasonic standing wave in a borosilicate glass capillary to capture plasma EVs among pre-seeded polystyrene microbeads through sound scatter interactions. We found that EVs could be reliably isolated from all plasma samples (n = 173) and that EV numbers increased more than 2-fold in the majority of patients after transplantation. Also, sufficient quantities of RNA for downstream microRNA (miRNA) analysis were obtained from all samples and EV miRNA profiles were found to differ from whole plasma profiles. As a proof of principle, expression of platelet-specific miR-142-3p in EVs was shown to correlate with platelet count kinetics after transplantation as expected. Importantly, we identified plasma EV miRNAs that were consistently positively correlated with infection and GvHD, respectively, as well as miRNAs that were consistently negatively correlated with these complications.

Conclusions

This study demonstrates that acoustic enrichment of EVs in a clinical biomarker study setting is feasible and that downstream analysis of acoustically-enriched EVs presents a promising tool for biomarker development in allo-HSCT. Certainly, these findings warrant further exploration in larger studies, which will have significant implications not only for biomarker studies in transplantation but also for the broad field of EV-based biomarker discovery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-020-00259-4.

Case report: A rare case of extravesical, extraperitoneal metastasis after transuretheral resection of urothelial carcinoma

Bladder perforation secondary to transurethral resection of bladder tumour (TURBT) increases the risk of tumour cell seeding and eventual extravesical metastasis. Here we presented a case where a patient with localised bladder tumour was initially managed with repeated TURBTs for tumour recurrence. Subsequently he was found to have extravesical pelvic metastasis. This was likely secondary to microperforation of bladder and tumour cell seeding. Microscopic bladder perforation is difficult to diagnose. However patients with confirmed bladder perforation during TURBT would justify systemic radiological cancer surveillance in view of higher risk of metastatic disease.

Acoustic Enrichment of Extracellular Vesicles from Biological Fluids

Extracellular vesicles (EVs) have emerged as a rich source of biomarkers providing diagnostic and prognostic information in diseases such as cancer. Large-scale investigations into the contents of EVs in clinical cohorts are warranted, but a major obstacle is the lack of a rapid, reproducible, efficient, and low-cost methodology to enrich EVs. Here, we demonstrate the applicability of an automated acoustic-based technique to enrich EVs, termed acoustic trapping. Using this technology, we have successfully enriched EVs from cell culture conditioned media and urine and blood plasma from healthy volunteers. The acoustically trapped samples contained EVs ranging from exosomes to microvesicles in size and contained detectable levels of intravesicular microRNAs. Importantly, this method showed high reproducibility and yielded sufficient quantities of vesicles for downstream analysis. The enrichment could be obtained from a sample volume of 300 μL or less, an equivalent to 30 min of enrichment time, depending on the sensitivity of downstream analysis. Taken together, acoustic trapping provides a rapid, automated, low-volume compatible, and robust method to enrich EVs from biofluids. Thus, it may serve as a novel tool for EV enrichment from large number of samples in a clinical setting with minimum sample preparation.

Isolated Posterior Acute Myocardial Infarction Presenting to an Emergency Department: Diagnosis and Emergent Fibrinolytic Therapy

Objectives

Isolated posterior acute myocardial infarction (AMI) is rare and possibly underdiagnosed. The incidence of misdiagnosis in the emergency department (ED) is unknown. Delayed diagnosis may prevent timely treatment, particularly emergent fibrinolytic therapy. We describe the experience of an urban ED on this rare condition.

Methodology

A six years and seven months case series of isolated posterior AMI of initial presentation (as identified by inpatient discharge/death ICD-9-CM diagnosis code) was studied. Patients not admitted from the ED, those who developed isolated posterior AMI only after admission and/or those with concomitant ST segment elevation AMI involving other anatomical locations of the heart (e.g. inferior or lateral walls), were excluded.

Results

Eleven cases were included in the study. All the nine cases with electrocardiograms available for review demonstrated features consistent with isolated posterior AMI. Eight out of the eleven (72.7%) cases were correctly diagnosed as isolated posterior AMI in the ED. The other three cases were treated as non-ST elevation myocardial infarction (NSTEMI). Nevertheless, their lack of the typical symptoms of acute coronary syndrome and delayed presentation (more than 12 hours) precluded them from fibrinolytics. Three of the eleven cases received fibrinolytics (all streptokinase). All three cases survived to discharge and there were no haemorrhagic complications. None of the cases underwent emergent percutaneous coronary intervention.

Conclusion

The majority of cases with isolated posterior AMI (72.7%) were diagnosed in the ED. Although three cases were interpreted as NSTEMI, the use of fibrinolytic reperfusion therapy was not affected.

Emergent Cranial Computed Tomography in the Evaluation of Adult Non-Trauma Patients in the Emergency Department

Objectives

To study the utilisation pattern of head computed tomography (CT) for non-trauma adult cases in an urban emergency department (ED) and the rate of clinically significant CT abnormalities. We also tried to identify any useful clinical indicators that could be used to predict abnormal scans.

Methodology

A one-year case series of adult non-trauma cranial CT scans ordered in an urban ED was studied. Patients less than 16 years old, with CT head done prior to presentation and/or attendance precipitated by trauma were excluded. Logistic regression was used to identify significant predictors for abnormal scans. Clinical indicators that were studied included age, altered mental status (AMS), headache and vomiting, elevated blood pressure, previous history of hypertension, Glasgow Coma Scale (GCS) and presence of focal neurological sign (FNS).

Results

183 adult non-trauma cranial CT scans were included in the study, and 109 (59.6%) CT scans revealed clinically significant abnormalities. Only AMS and FNS were found to be statistically significant in predicting abnormal scans. Patients with AMS had a 2.5 times (95% CI: 1.1 to 5.8) higher odds for an abnormal scan compared to those without AMS, adjusting for FNS. Patients with FNS had adjusted odds of 8.9 (95% CI: 4.2 to 18.8).

Conclusion

This study reports a high (59.6%) rate of abnormal adult non-trauma cranial CT compared with previous studies. Altered mental status and the presence of focal neurological sign are significant predictors for an abnormal scan. They should serve as useful criteria when devising utilisation strategies for emergency non-trauma cranial CT in future studies.

Human Primary Bone Marrow Mesenchymal Stromal Cells and Their in vitro Progenies Display Distinct Transcriptional Profile Signatures

Bone marrow mesenchymal stromal cells (BM-MSCs) are a rare population of cells that gives rise to skeletal tissues and the hematopoietic stroma in vivo. Recently, we have demonstrated that BM-MSCs fulfill stringent in vivo stem cell criteria when propagated as non-adherent mesenspheres but not as adherent-cultured cells. Motivated by these profound functional differences, the current study aimed to identify potential important MSC regulators by investigating global gene expression profiles of adherent and non-adherent culture-derived BM-MSCs in comparison with primary BM-MSCs. A substantial number of genes were differentially expressed between primary and culture-expanded cells already early upon culture, and numerous genes were found to be different when comparing adherent and non-adherent BM-MSCs. Cluster analysis identified 16 sets of genes of which two displayed comparable gene expression levels in primary and non-adherent cultured cells, but not in adherent cultured cells. This pattern suggested that these clusters contained candidate regulators of BM-MSCs. Gene expression differences were confirmed for selected genes and BM-MSC transcription factors by protein analysis and RT-PCR, respectively. Taken together, these data demonstrated profound gene expression changes upon culture of primary BM-MSCs. Moreover, gene cluster differences provide the basis to uncover the regulatory mechanisms that control primary and cultured BM-MSCs.

Human Non-Hematopoietic CD271pos/CD140alow/neg Bone Marrow Stroma Cells Fulfill Stringent Stem Cell Criteria in Serial Transplantations

Human bone marrow contains a population of non-hematopoietic stromal stem/progenitor cells (BMSCs), which play a central role for bone marrow stroma and the hematopoietic microenvironment. However, the precise characteristics and potential stem cell properties of defined BMSC populations have not yet been thoroughly investigated. Using standard adherent colony-forming unit fibroblast (CFU-F) assays, we have previously shown that BMSCs were highly enriched in the nonhematopoietic CD271^pos/CD140a^low/neg fraction of normal adult human bone marrow. In this study, we demonstrate that prospectively isolated CD271^pos/CD140a^low/neg BMSCs expressed high levels of hematopoiesis supporting genes and signature mesenchymal and multipotency genes on a single cell basis. Furthermore, CD271^pos/CD140a^low/neg BMSCs gave rise to non-adherent sphere colonies (mesenspheres) with typical surface marker profile and trilineage in vitro differentiation potential. Importantly, serial transplantations of CD271^pos/CD140a^low/neg BMSC-derived mesenspheres (single cell and bulk) into immunodeficient NOD scid gamma (NSG) mice showed increased mesensphere numbers and full differentiation potential after both primary and secondary transplantations. In contrast, BMSC self-renewal potential decreased under standard adherent culture conditions. These data therefore indicate that CD271^pos/CD140a^low/neg BMSCs represent a population of primary stem cells with MSC phenotype and sphere-forming capacity that fulfill stringent functional stem cell criteria in vivo in a serial transplantation setting.

Insights into the key roles of proteoglycans in breast cancer biology and translational medicine

Proteoglycans control numerous normal and pathological processes, among which are morphogenesis, tissue repair, inflammation, vascularization and cancer metastasis. During tumor development and growth, proteoglycan expression is markedly modified in the tumor microenvironment. Altered expression of proteoglycans on tumor and stromal cell membranes affects cancer cell signaling, growth and survival, cell adhesion, migration and angiogenesis. Despite the high complexity and heterogeneity of breast cancer, the rapid evolution in our knowledge that proteoglycans are among the key players in the breast tumor microenvironment suggests their potential as pharmacological targets in this type of cancer. It has been recently suggested that pharmacological treatment may target proteoglycan metabolism, their utilization as targets for immunotherapy or their direct use as therapeutic agents. The diversity inherent in the proteoglycans that will be presented herein provides the potential for multiple layers of regulation of breast tumor behavior. This review summarizes recent developments concerning the biology of selected proteoglycans in breast cancer, and presents potential targeted therapeutic approaches based on their novel key roles in breast cancer.

Cell surface heparan sulfate proteoglycans control adhesion and invasion of breast carcinoma cells

Background

Cell surface proteoglycans interact with numerous regulators of cell behavior through their glycosaminoglycan chains. The syndecan family of transmembrane proteoglycans are virtually ubiquitous cell surface receptors that are implicated in the progression of some tumors, including breast carcinoma. This may derive from their regulation of cell adhesion, but roles for specific syndecans are unresolved.

Methods

The MDA-MB231 human breast carcinoma cell line was exposed to exogenous glycosaminoglycans and changes in cell behavior monitored by western blotting, immunocytochemistry, invasion and collagen degradation assays. Selected receptors including PAR-1 and syndecans were depleted by siRNA treatments to assess cell morphology and behavior. Immunohistochemistry for syndecan-2 and its interacting partner, caveolin-2 was performed on human breast tumor tissue arrays. Two-tailed paired t-test and one-way ANOVA with Tukey’s post-hoc test were used in the analysis of data.

Results

MDA-MB231 cells were shown to be highly sensitive to exogenous heparan sulfate or heparin, promoting increased spreading, focal adhesion and adherens junction formation with concomitantly reduced invasion and matrix degradation. The molecular basis for this effect was revealed to have two components. First, thrombin inhibition contributed to enhanced cell adhesion and reduced invasion. Second, a specific loss of cell surface syndecan-2 was noted. The ensuing junction formation was dependent on syndecan-4, whose role in promoting actin cytoskeletal organization is known. Syndecan-2 interacts with, and may regulate, caveolin-2. Depletion of either molecule had the same adhesion-promoting influence, along with reduced invasion, confirming a role for this complex in maintaining the invasive phenotype of mammary carcinoma cells. Finally, both syndecan-2 and caveolin-2 were upregulated in tissue arrays from breast cancer patients compared to normal mammary tissue. Moreover their expression levels were correlated in triple negative breast cancers.

Conclusion

Cell surface proteoglycans, notably syndecan-2, may be important regulators of breast carcinoma progression through regulation of cytoskeleton, cell adhesion and invasion.

Fell-Muir Lecture: Syndecans: from peripheral coreceptors to mainstream regulators of cell behaviour

In the 25 years, as the first of the syndecan family was cloned, interest in these transmembrane proteoglycans has steadily increased. While four distinct members are present in mammals, one is present in invertebrates, including C. elegans that is such a powerful genetic model. The syndecans, therefore, have a long evolutionary history, indicative of important roles. However, these roles have been elusive. The knockout in the worm has a developmental neuronal phenotype, while knockouts of the syndecans in the mouse are mild and mostly limited to post-natal rather than developmental effects. Moreover, their association with high-affinity receptors, such as integrins, growth factor receptors, frizzled and slit/robo, have led to the notion that syndecans are coreceptors, with minor roles. Given that their heparan sulphate chains can gather many different protein ligands, this gave credence to views that the importance of syndecans lay with their ability to concentrate ligands and that only the extracellular polysaccharide was of significance. Syndecans are increasingly identified with roles in the pathogenesis of many diseases, including tumour progression, vascular disease, arthritis and inflammation. This has provided impetus to understanding syndecan roles in more detail. It emerges that while the cytoplasmic domains of syndecans are small, they have clear interactive capabilities, most notably with the actin cytoskeleton. Moreover, through the binding and activation of signalling molecules, it is likely that syndecans are important receptors in their own right. Here, an overview of syndecan structure and function is provided, with some prospects for the future.

The influence of surgical factors on dislocation of the meniscal bearing after Oxford medial unicompartmental knee replacement: a case-control study

The aim of this study was to evaluate the risk factors for dislocation of the bearing after a mobile-bearing Oxford medial unicompartmental knee replacement (UKR) and to test the hypothesis that surgical factors, as measured from post-operative radiographs, are associated with its dislocation From a total of 480 UKRs performed between 2001 and 2012, in 391 patients with a mean age of 66.5 years (45 to 82) (316 female, 75 male), we identified 17 UKRs where bearing dislocation occurred. The post-operative radiological measurements of the 17 UKRs and 51 matched controls were analysed using conditional logistic regression analysis. The post-operative radiological measurements included post-operative change in limb alignment, the position of the femoral and tibial components, the resection depth of the proximal tibia, and the femoral component-posterior condyle classification. We concluded that a post-operative decrease in the posterior tibial slope relative to the pre-operative value was the only significant determinant of dislocation of the bearing after medial Oxford UKR (odds ratio 1.881; 95% confidence interval 1.272 to 2.779). A post-operative posterior tibial slope < 8.45° and a difference between the pre-operative and post-operative posterior tibial slope of > 2.19° may increase the risk of dislocation.

Evaluation of anatomical landmark position differences between respiration-gated MRI and four-dimensional CT for radiation therapy in patients with hepatocellular carcinoma

OBJECTIVE

To measure the accuracy of position differences in anatomical landmarks in gated MRI and four-dimensional CT (4D-CT) fusion planning for radiation therapy in patients with hepatocellular carcinoma (HCC).

METHODS

From April to December 2009, gated MR and planning 4D-CT images were obtained from 53 inoperable HCC patients accrued to this study. Gated MRI and planning 4D-CT were conducted on the same day. Manual image fusions were performed by matching the vertebral bodies. Liver volumes and three specific anatomical landmarks (portal vein conjunction, superior mesenteric artery bifurcation, and other noticeable points) were contoured from each modality. The points chosen nearest the centre of the four landmark points were compared to measure the accuracy of fusion.

RESULTS

The average distance differences (±standard deviation) of four validation points were 5.1 mm (±4.6 mm), 5.6 mm (±6.2 mm), 5.4 mm (±4.5 mm) and 5.1 mm (±4.8 mm). Patients who had ascites or pulmonary disease showed larger discrepancies. MRI-CT fusion discrepancy was significantly correlated with positive radiation response (p<0.05).

CONCLUSIONS

Approximately 5-mm anatomical landmark positional differences in all directions were found between gated MRI and 4D-CT fusion planning for HCC patients; the gap was larger in patients with ascites or pulmonary disease.

ADVANCES IN KNOWLEDGE

There were discrepancies of approximately 5 mm in gated MRI-CT fusion planning for HCC patients.

Regulation of ribosome synthesis in Escherichia coli: effects of temperature and dilution rate changes

The effect of temperature on the synthesis of ribosome in Escherichia coli K-12 was investigated. In continuous fermentation, the total and functioning ribosome contents decreased with increasing temperature, while the non-functioning ribosome content remained unchanged. Cells contained higher amounts of functioning ribosome at lower temperatures to compensate for the decrease in translational activity. A transient study was performed to investigate the dynamic response of the cell to changes in the dilution rate. In response to the dilution rate shift-up, the cell mass decreased until the cells produced a sufficient amount of ribosomes to support the new higher growth rate. However, the response to the dilution rate shift-down resulted in an immediate increase in cell mass. This may be due to the fact that the cell already contains enough ribosomes to support a lower growth rate corresponding to the new low dilution rate. Based on the experimental results, a mathematical model was developed to describe the cell growth at transient as well as steady states. The total ribosome content was included as a variable because it affects the growth rate of the cell.

Optimization of fermentation processes using recombinant Escherichia coli with the cloned trp operon

Optimal operating conditions have been determined for recombinant Escherichia coli cells in a fed-batch and two-stage continuous fermentors. The model expression system used in this article was the E. coli trp promoter cloned on plasmids. Model equations for cell growth and cloned-gene expression have been formulated and used to evaluate process performances under different operating modes. The operating variables manipulated for maximum performance include the timing of IAA addition to derepress transcription from the trp promoter. The total operating period and the nutrient concentration profile during fermentations. For a fed-batch mode, the performance was significantly improved by adjusting the IAA addition (environmental switch) time relative to the total operation period. It was found that the optimal switching time exists for a given total operation period. For a two-stage continuous fermentation system, the productivity is more sensitive to the combination of the dilution rates than to the volume ratio of two reactors. In general, as long as the down time is less than the total operation time in the fed-batch mode, the fed-batch mode gives higher productivity than the two-stage continuous system.

Assessment of Physical Activity Level among Individuals with Type 2 Diabetes Mellitus at Cheras Health Clinic, Kuala Lumpur

A cross-sectional study was carried out to assess the physical activity levels among patients with type 2 diabetes mellitus (DM) at Cheras Health Clinic in Kuala Lumpur. A total of 132 subjects (62 men and 70 women) aged 30 years and above participated in this study. Data was collected using an interview based questionnaire to obtain socio-demographic and health profile information. Physical activity was assessed using a shortened version of the International Physical Activity Questionnaire (IPAQ). Anthropometric measurements and body fat were also taken. Glycaemic status, that is, HbA1c, fasting blood sugar (FBS) and 2 hours post-prandial (2-HPP) were obtained from medical records. Results showed that the mean age of the patients was 51.9 + 5.8 years. The majority of patients had poor glycaemic control based on HbA1c (70.7%), FBS (71.9%) and 2HPP (85.4%). Patients who were unmarried and aged(60 years and above had a lower physical activity level (p< 0.05). In the older age group, low physical activity was associated with poor glycaemic control (p< 0.05). Patients in the moderate and high physical activity level were motivated to perform physical activity so as to be healthy (68.1%). Low physical activity level among patients was due to lack of time (54.5%) and lack of energy (21.2%). In conclusion, physical activity levels of the patients were unsatisfactory and associated with poor glycaemic control, especially in the elderly. There is a need to encourage diabetic patients to undertake regular physical activity in order to achieve optimal glycaemic control.

Acute naphthalene poisoning following the non-accidental ingestion of mothballs

Ingestional naphthalene mothball poisoning leading to prolonged haemolysis and methaemoglobinaemia can present with diagnostic and therapeutic challenges. A 19-year-old woman ingested 12 mothballs, and presented two days later with haemolysis and methaemoglobinaemia. She was treated with red blood cell transfusions, intravenous methylene blue, N-acetylcysteine and ascorbic acid. Continuous venovenous haemofiltration was conducted for 45 hours. Haemolysis with anaemia and methaemoglobinaemia persisted even after five days post-ingestion. Clinical and biochemical parameters improved. We describe a case of ingestional naphthalene poisoning with a good outcome after treatment.

Pathotypes and genetic relationship of worldwide collections of Elsinoë spp. causing scab diseases of citrus

Two scab diseases are recognized currently on citrus: citrus scab, caused by Elsinoë fawcettii, and sweet orange scab, caused by E. australis. Because the two species cannot be reliably distinguished by morphological or cultural characteristics, host range and molecular methods must be used to identify isolates. Four pathotypes of E. fawcettii and two of E. australis have been described to date based on host range. The host specificity and genetic relationships among 76 isolates from Argentina, Australia, Brazil, Korea, New Zealand, and the United States were investigated. Based on pathogenicity tests on eight differential hosts, 61 isolates were identified as E. fawcettii and 15 as E. australis. Of 61 isolates of E. fawcettii, 24 isolates were identified as the Florida broad host range (FBHR) pathotype, 7 as the Florida narrow host range (FNHR) pathotype, 10 as the Tryon's pathotype, and 3 as the "Lemon" pathotype. Two new pathotypes, the "Jingeul" and the satsuma, rough lemon, grape-fruit, clementine (SRGC), are described, and four isolates did not fit into any of the known pathotypes of E. fawcettii. Of the 15 isolates of E. australis from Argentina and Brazil, 9 belonged to the sweet orange pathotype and 6 from Korea to the natsudaidai pathotype. E. fawcettii and E. australis were clearly distinguishable among groups by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) assays and the E. fawcettii group was divided into three subgroups, A-1, A-2, and A-3. The A-1 group was composed of the FBHR, FNHR, and SRGC pathotypes; some Lemon pathotypes; and the uncertain isolates. The A-2 subgroup included all of the Tryon's pathotype isolates and one of the three Lemon pathotype isolates and the A-3 group contained the Jingeul pathotype isolates. E. australis was differentiated into two groups: B-1, the natsudaidai pathotype isolates, and B-2, the sweet orange pathotype isolates. Isolates of E. fawcettii and E. australis were clearly distinguishable by sequence analysis of the internal transcribed spacer (ITS) region and the translation elongation factor 1 alpha (TEF) gene. There were also fixed nucleotide differences in the ITS and TEF genes that distinguished subgroups separated by RAPD-PCR within species. We confirmed two species of Elsinoë, two pathotypes of E. australis, and at least six pathotypes of E. fawcettii and described their distribution in the countries included in this study.

Arthrodesis of the knee using cannulated screws

We retrospectively evaluated eight patients who underwent arthrodesis of the knee using cannulated screws. There were six women and two men, with a mean age of 53 years. The indications for arthrodesis were failed total knee arthroplasty, septic arthritis, tuberculosis, and recurrent persistent infection. Solid union was achieved in all patients at a mean of 6.1 months. One patient required autogenous bone graft for delayed union. One suffered skin necrosis which was treated with skin grafting. The mean limb-length discrepancy was 3.1 cm. On a visual analogue scale, the mean pain score improved from 7.9 to 3.3. According to the Knee Injury and Osteoarthritis Outcome score quality of life items, the mean score improved from 38.3 pre-operatively to 76.6 at follow-up. Cannulated screws provide a high rate of union in arthrodesis of the knee with minimal complications, patient convenience, and a simple surgical technique.

Effects of irradiation on cytokine production in a mouse model of Behçet's disease

OBJECTIVE

Low-dose whole-body irradiation is known to have anti-inflammatory effects. The objectives of this study were to verify that cytokine augmentation is induced by irradiation in vivo, and to assess the effectiveness of radiation in treating Behçet's disease (BD).

METHODS

Whole-body and half-body irradiation with single doses of 10cGy, 2Gy and 10Gy were delivered to normal mice, and cytokine and chemokine levels were analyzed in PBMC and sera. BD-like mice were treated with low-dose, half-body 10cGy irradiation.

RESULTS

In normal mice, PBMC cytokine mRNA levels peaked four days after irradiation. Of the cytokines and chemokines examined, the levels of IL-4, IL-6, IL-12p40, TNF-alpha, TGF-b, MIP-1alpha and IL-18 were all influenced by radiation treatment. Of these, IL-4, an ameliorating factor for BD, was the most elevated following low-dose irradiation (10cGy group). FACS analysis showed intracellular IL-4-staining of 7.24+/-0.92% of PBMC from irradiated mice compared to 1.3+/-0.1% from non-irradiated, normal mice (p<0.005). Serum IL-4 levels were also significantly increased (6.08+/-1.7 pg/ml) relative to control (1.83+/-0.8; p<0.005).

CONCLUSION

Augmentation of cytokine production may contribute to the anti-inflammatory effects of low dose irradiation and amelioration of BD symptoms in this mouse model.

Determination of molecular types and genetic heterogeneity ofCryptococcus neoformansandC. gattiiin Malaysia

The molecular types and genetic heterogeneity of Cryptococcus neoformans and C. gattii clinical isolates in Malaysia were determined in this study. Of 44 C. neoformans collected between 1980 and 2003, 42 (95.5%) were molecular type VNI, 2 (4.5%) were molecular type VNII. Of 17 C.gattii isolates, 13 (76.5%) were molecular type VGI, and 4 (23.5%) were molecular type VGII. A difference was noted when comparing the molecular types of cryptococcal isolates in the earlier and recent cases of cryptococcosis. While both molecular types VNI and VGI were equally predominant in the earlier cases of cryptococcosis, VNI was the most predominant molecular type isolated from the recent cases. VNII was a new molecular type, isolated from 5.1% of the recent cases. All the bird dropping isolates were molecular type VNI. The genetic heterogeneity of the two predominant molecular types, i.e., VNI, VGI clinical isolates and bird dropping isolates of C. neoformans were further determined by polymerase chain reaction (PCR) fingerprinting method, using (GTG)5 as single primer. Two clusters of cryptococcal isolates were distinguished at 68.5% of similarity, with cluster I consisting of VNI isolates and cluster II consisting of VGI isolates. Each cluster was further subdivided into three subtypes at >/=80% of similarity. Fourteen bird dropping isolates were grouped into a subtype within VN1, sharing 82.7% of similarity with the clinical isolates. A higher degree of similarities, ranging from 93.4-97.6% was noted between 3 bird dropping isolates with the clinical isolates in another subtype. This study demonstrated the existence of various molecular types of C. neoformans isolates in Malaysia and the genetic heterogeneity within the predominant molecular types. The study also provides evidence for genetic relatedness of clinical isolates with bird dropping isolates in the environment.

Kinetics of L-lysine fermentation: a continuous culture model incorporating oxygen uptake rate

For process design and optimization, it is essential to have a mathematical model that represents the system well. Many past studies do not go beyond empirically fitting experimental data. In the present study, an unstructured model incorporating oxygen uptake and dissolved oxygen concentration was developed for a continuous culture of L-lysine. Specific rate expressions of cell growth, substrate consumption, product formation, and oxygen uptake were developed and incorporated in the model. The model predicts very well the effects of operational parameters, such as the dilution rate and the feed substrate concentration. It is also able to predict the unsteady-state dynamics of continuous L-lysine fermentation.

Intra-articular ganglion cysts of the knee: clinical and MR imaging features

The purpose of this study was to present clinical and MR imaging features of intra-articular ganglion cysts of the knee. Retrospective review of 1685 consecutive medical records and MR examinations of the knee performed at three imaging centers allowed identification of 20 patients (13 men and 7 women; mean age 35 years), in whom evidence of intra-articular ganglion cyst was seen. Of the 20 ganglion cysts, 5 were found in the infrapatellar fat pad, 10 arose from the posterior cruciate ligament, and 5 from the anterior cruciate ligament. Three of five patients with ganglion cyst in the infrapatellar fat pad had a palpable mass. In 7 of 15 patients with ganglion cyst in the intercondylar notch, exacerbation of pain occurred in a squatting position. On four MR arthrographies, ganglion cysts were an intra-articular round, lobulated, low signal intensity lesion. Five cases of fat-suppressed contrast-enhanced T1-weighted SE images demonstrated peripheral thin rim enhancement. The clinical presentation of intra-articular ganglion cyst is varied according to its intra-articular location. The MR appearance of intra-articular ganglion cyst is characteristic and usually associated with the cruciate ligament or the infrapatellar fat pad. Magnetic resonance arthrography has no definite advantage over conventional MR in the evaluation of the lesion. For intra-articular ganglion cyst in the infrapatellar fat pad, fat-suppressed contrast-enhanced MR imaging could be useful, because a thin, rim-enhancing feature of intra-articular ganglion cyst allows it to be distinguished from synovial hemangioma and synovial sarcoma.

Out of hospital cardiac arrests--the experience of one hospital in Singapore

In Singapore, all public emergency ambulances are equipped with semi-automatic external defibrillators and the crew is trained in their use. This is the first paper from Singapore reporting the survival rate in patients presenting to an urban public hospital with acute coronary syndrome (ACS) who developed out-of-hospital cardiac arrest (OHCA). All consecutive patients who presented to the ED of a public hospital with OHCA or ACS were surveyed from 1 April 1999 to 30 September 1999. There were 392 patients among whom 115 (28.5%) had OHCA. There was no significant difference in age and gender distribution between the OHCA and non-OHCA patients. More than 2/3 of the OHCA patients had no report of chest pain or breathlessness before they collapsed. Forty five (39.1%) of the 115 OHCA patients were noted to have initial rhythms of ventricular tachycardia (VT) or ventricular fibrillation (VF) and received pre-hospital defibrillation. The mean time from collapse to first DC shock was 12.07+/-7.2 min. Twenty (17.4%) of the OHCA patients had return of spontaneous circulation after resuscitation in the ED. Four patients (3.5%), all with an initial rhythm of VF were discharged alive from the hospital. Much remains to be done to reduce the time interval to first DC shock for the OHCA group.

Meniscal flounce on MR: correlation with arthroscopic or surgical findings

The purpose of this study was to investigate the frequency of the meniscal flounce on MR imaging in patients who underwent arthroscopy or open surgery due to symptoms related to internal derangement of the knee, and to investigate associated findings in patients with meniscal flounce by comparing and analyzing the findings from MR imaging and surgery. MR images obtained from 116 knees before surgery were reviewed retrospectively. Seven medial menisci showed buckled, wavy flounce on sagittal MR images. None of the lateral menisci showed flounce. We reviewed the surgical records of all seven patients and the videotapes of six of the patients undergoing arthroscopy or open surgery. The frequency of flounce on sagittal MR images was 6.0% in the medial meniscus and was completely absent in the lateral meniscus. On coronal MR images, the truncated appearance of the affected meniscus was demonstrated in five patients, and a valgus deformity was seen in three patients. Five patients showed a moderate to large amount of joint effusion. On MR imaging and in surgery, ligament injuries were found in six patients (six medial collateral ligament injuries, five anterior cruciate ligament injuries, and two posterior cruciate ligament injuries). Non-specific synovitis was found in the one remaining patient. In the surgery of all seven patients, no tears were found at the meniscus itself showing flounce. In conclusion, the meniscal flounce seen on sagittal MR imaging can be a rare appearance of a transient distortion of a normal meniscus due to a valgus deformity caused by a MCL tear and/or due to an external rotation induced by cruciate ligament injury or positioning of knee joint within the magnet. The meniscal flounce should be interpreted carefully because it frequently appears truncated on the coronal scan and can simulate a meniscal tear.

Vision screening of 4-year-old children in Singapore

AIM OF THE STUDY

To evaluate the feasibility of an improved visual acuity screening program for Singapore 4-year-old preschool children and to draw up an appropriate referral criteria as well as evaluating the rates and outcomes of these referrals.

METHOD

A total of 450 children aged 4 to 4 1/2 years, who attended 3 polyclinics of the Family Health Service (FHS) for their 4-year-old Developmental Health Screening during the study period from 1/4/1997 to 30/6/1997 were recruited for the study. Children who were tested with Snellen (or Sloan) visual acuity chart resulting in visual acuity of 6/9 or worse, or failed to pass the 3 mm medium plate at 30 cm distance (300 seconds of arc) in the Frisby Stereotest, or were found to have strabismus, or were untestable in either visual acuity test or stereotest were offered referral to ophthalmologists in the hospitals for specialist assessment.

RESULT

82.7% of the 450 children were successfully screened with Snellen (or Sloan) chart while 91.6% were successfully screened with Frisby Stereotest. In all, 180 children were evaluated by ophthalmologists. Majority of the children were referred because of their abnormal visual acuity test while only 2 children were referred for failing stereotest alone. Among the 180 children referred, 63 (35.0%) were found to have refractive errors for which spectacles were prescribed. Eight children had amblyopia and 2 children had strabismus which were not detected at the polyclinic screening. The untestable children evaluated had significantly higher abnormality rate (37.5%) than that of children who had 6/9 vision (8.8%) therefore they should be offered referral for further evaluation. There was high "refused referral" rate of 39.0%. Parents of children who were untestable or had 6/9 vision were found to be more likely to refuse offer of referral. If these two groups of children were excluded, the "refused referral" rate dropped to 13.3%. When the referral criteria for visual acuity was reset at 6/12 instead of 6/9, the referral rate dropped from 39.6% to a more manageable 26.7% and the positive predictive value improved from 35.4% to 48.3% and none of the children with amblyopia were missed being screened-out.

CONCLUSION

The study confirmed the feasibility of doing visual acuity screening at 4 to 41/2 year-old. The referral criteria for abnormal visual acuity should be set at 6/12. The efficacy of adding Frisby stereotest needs further evaluation.

Noninvasive light-reflection technique for measuring soft-tissue stretch

A novel, to our knowledge, sensor for measuring the stretch in soft tissues such as skin is described. The technique, which is a modification of two-dimensional polarization imaging, uses changes in the reflectivity of polarized light as a monitor of skin stretch. Measurements show that the reflectivity increases with stretch. Measurements were made on guinea pig skin and on nonbiological materials. The changes in reflectivity result from the changes that take place in the interface roughness between skin or material layers and the consequential changes in the diffuse reflective characteristics of the skin. Conceptually, as the roughness of an interface decreases, a smoother reflecting interface is produced, resulting in a commensurate increase in specular reflection. A simple roughness model correctly predicts the main experimental results. Results can be extended easily to real-time stretch analysis of large tissue areas that would be applicable for predicting stresses in skin during and after the surgical closure of wounds.

Why do patients complain? A primary health care study

BACKGROUND/AIM OF STUDY

Patient complaints are indications of their dissatisfaction with the service received. With increasing patient expectations, we need to address this issue for a more satisfying relationship between healthcare provider and user. The objective of this study was to analyse the basis of patients' complaints and to make recommendations to reduce its incidence.

METHOD

This is a retrospective descriptive study of all complaints to the Family Health Service between January 1994 and December 1995. All complaints, investigations and replies to complainants were examined and analysed by the authors to determine the reasons for complaints and their justification.

RESULTS

There were 226 complaint cases out of 5,620,834 attendances in two years, giving the complaints rate of 4 per 100,000 attendances per year. The complaint rate was highest for the 20-59-year age group and lowest in the 10-19-year age group (3.7 and 2.0 per 100,000 attendances respectively). Sixty-four percent of complaints were verbal and the rest were written. Forty-seven percent of the complaints were made by relatives and 46% were self-complaints. The main reasons for complaints were related to attitude/conduct (28.8%), professional skills (17.8%), patient expectations (16.2%), waiting time (10.0%) and communication (7.8%). Forty-three percent of complaints were evaluated as justifiable, 38% not justifiable and 19% inconclusive. There were no particular sex or ethnic group differences.

CONCLUSION

The rate of complaints in Family Health Service was low. Healthcare personnel need to pay attention to areas related to attitude/conduct, professional skills, patient expectations, waiting time and communication.

Characterization of bacteriophage lambda Q- mutant for stable and efficient production of recombinant protein in Escherichia coli system

We previously demonstrated that the lambda system integrated into the host chromosome can overcome the instability encountered in continuous operations of unstable plasmid-based expression vectors. High stability of a cloned gene in a lysogenic state and a high copy number in a lytic state provide cloned-gene stability and overexpression in a two-stage continuous operation. But the expression by the commonly used S- mutant lambda was only twice as high as that of the single copy. To increase the expression in the lambda system, we constructed a Q- mutant lambda vector that can be used in long-term operations such as a two-stage continuous operation. The Q- mutant phage lambda is deficient in the synthesis of proteins involved in cell lysis and lambda DNA packaging, while the S- mutant is deficient in the synthesis of one of two phage proteins required for lysis of the host cell and liberation of the progeny phage. Therefore, it is expected that the replicated Q- lambda DNA containing a cloned gene would not be coated by a phage head and would remain naked for ample expression of the cloned gene and host cells would not lyse easily and consequently would produce larger amounts of cloned-gene products. The beta-galactosidase expression per unit cell by the Q- mutant in a lytic state was about 30 times higher than that in a lysogenic state, while the expression by the commonly used S- mutant in a lytic state was twice as high as that in a lysogenic state. The optimal switching time of the Q- mutant from the lysogenic state to the lytic state for the maximum production of beta-galactosidase was 5.3 h, which corresponds to an early log phase in the batch operation.

Computerised prostate boundary estimation of ultrasound images using radial bas-relief method

A new method is presented for automatic prostate boundary detection in ultrasound images taken transurethrally or transrectally. This is one of the stages in the implementation of a robotic procedure for prostate surgery performed by a robot known as the robot for urology (UROBOT). Unlike most edge detection methods, which detect object edges by means of either a spatial filter (such as Sobel, Laplacian or something of that nature) or a texture descriptor (local signal-to-noise ratio, joint probability density function etc.), this new approach employs a technique called radial bas-relief (RBR) to outline the prostate boundary area automatically. The results show that the RBR method works well in the detection of the prostate boundary in ultrasound images. It can also be useful for boundary detection problems in medical images where the object boundary is hard to detect using traditional edge detection algorithms, such as ultrasound of the uterus and kidney.

Bioreactor studies on temperature induction of the Q- mutant of bacteriophage lambda in Escherichia coli

The parasite-host interactions between bacteriophage lambda (denoted as lambda) and Escherichia coli bacteria were studied in different bioreactor systems. Although the replicated lambda-DNA of Q- mutant remains naked for a longer time to reach a high gene expression, the epidemic of lambda-infection and the coevolutionary host-phage relations limit the temperature induction efficiency. The temperature induction is strongly dependent upon the susceptible population density at which lambda-infection is activated. Maximum beta-galactosidase expression occurs at the threshold of the infection system. According to this concept, the lethal level of parasitic lambda to hosts is approx. 5 x 10(6) pfu/ml. Since a higher phage lambda burden is exerted upon host cells at a low ODsh, the system moves towards virulence reduction for total survival. Prey-predator isocline analysis is used to consider the stability of the outcome of infection. The host growth has a destabilizing effect at lower population densities and a stabilization effect at higher population. Based upon the predictions, a substrate enrichment enhances bacterial growth and reporter protein production. However, the operations still need to follow the trajectory of threshold tie line to guarantee maximal productivity. Since the washout of infected cells reduces induction performance in continuous cultures, a batch mode of operation is better than continuous stirred tank reactor (CSTR) mode to achieve high gene expression. The threshold cell density regulates induction performances and therefore produces the optimal gene expression by maintaining maximal viable cells that provide sufficient resources for lambda expression.

The field testing of Denver Developmental Screening Test Singapore: a Singapore version of Denver II Developmental Screening Test

The Denver Developmental Screening Test, Singapore (DDST, Singapore), a Singapore version of the Denver II Developmental Screening Test, was field-tested, using trained staff nurses as testers, on 2459 children (known cases excluded), in 5 key ages of 3 months, 9 months, 17 months, 37 months and 60 months. Only 2.6% (65) of the parents suspected developmental problems in their children before screening. Taking children with "questionable" (7.2%), "abnormal" (3.7%) and "untestable" (1.7%) scores as the screened-out cases, the DDST, Singapore had a screened-out rate of 12.6%. A total of 171 screened-out cases and 168 "normal" children were also evaluated by the Development Assessment Clinic (DAC) of the Singapore General Hospital and the results were compared in these 2 groups of children. Among the screened-out cases, 16.6% were confirmed or suspected to have neuro-developmental disorders (NDDs) by the DAC. The computed NDD rate in the study sample was 5.3%. Based on a single DDST, Singapore test result, there was a high false positive rate of 83.5% and lower false negative rate of 3.7% compared to the DAC assessment. However, the high false positive rate would be significantly reduced by doing a repeat screening test on the "questionable" cases and having the screened-out cases assessed by trained primary health care doctors. In conclusion, no major revision is needed in the scoring criteria suggested in the current version of DDST, Singapore. It is a useful tool in identifying children who will otherwise be missed without formal screening.

Temperature induction of bacteriophage lambda mutants in Escherichia coli

The paper presents temperature induction in Escherichia coli cells with phage lambda on the target-protein production and cell growth. Replicated lambda-DNA particles in the Q- and S- mutants remain naked for a longer time by preventing DNA packaging and cell lysis, and therefore the expression of the foreign genes is high. However, the parasitic infection of phage-lambda causes on significant losses of host cell viability in the induction phase. The temperature effects on cell growth and targeted-gene product formation were investigated. Gene amplification was found to be growth phase dependent for both Qam73 (Q mutation) and Sam100 (S mutation) mutants. Maximum induction occurs in the early exponential phase and under the optimal cell density. The total beta-galactosidase activity at this optimal induction condition increases roughly 8-10-fold with respect to that without thermal induction. To maximize the induction efficiency for the gene-product beta-galactosidase activity, several operating parameters were investigated. In this study, temperature induction is strongly dependent upon the population density of 'susceptible' cells at which time the temperature is shifted to 38-42 degrees C. This may be due to the 'threshold' population density to regulate the infection of lambda to hosts and control the productivity of target gene expression.

Least-squares fitting of the phase map obtained in phase-shifting electronic speckle pattern interferometry

A new method has been developed to remove noise from the deformation phase map obtained by a phase-shifting electronic speckle pattern interferometry. Unlike usual methods, it estimates almost noise-free phase values directly from the distributions of the intensity differences of four interference patterns by a least-squares fit. The fluctuations of uniform deformation phases are reduced to less than 0.05 rad with a 5 x 5 pixel fitting window. The so-called sawtooth phase jumps that are due to the use of arctangent functions are retained sharply in this method.

cAMP, ethanol, and CO2 production with the addition of D-glucose anomer to starved yeast cells

cAMP, ethanol, and CO2 production in starved yeast cells after the addition of D-glucose anomer was measured and compared over a wide range of anomer concentrations. At 1.0 g/l or higher concentrations, the addition of beta-D-glucose resulted in a higher cAMP peak. beta-D-glucose was more rapidly metabolized to ethanol and CO2 than alpha-D-glucose, although there was no notable difference in the uptake rates of the two anomers. At 0.4 g/l D-glucose anomer, the differences in cAMP and ethanol production rates for the two anomers were not significant. At 0.2 g/l D-glucose anomer or lower concentrations, ethanol production with alpha-D-glucose was higher than that with beta-D-glucose. The uptake rate of alpha-D-glucose was higher than that of beta-D-glucose at this low concentration.

Tyrosinase production in recombinant E. coli containing trp promoter and ubiquitin sequence

We have successfully expressed the active tyrosinase of Streptomyces antibioticus in Escherichia coli under the control of the trp promoter by fusing the sequence to the ORF438 gene. Because our attempt to connect the polycistronic gene of ORF438 and tyrosinase directly to the trp promoter of E. coli resulted in the expression of functionally inactive tyrosinase, we decided to fuse the COOH-terminus of ubiquitin sequence to the NH2-terminus of ORF438. Ubiquitin fusion has been shown to augment the yield of cloned gene products in E. coli by increasing the stability or translational efficiency of the fusion proteins. As a result, E. coli transformants harboring a plasmid pTRUBF that contains the ubiquitin-fused ORF438 and the tyrosinase gene produced the strong black pigment of melanin. About 300 units of tyrosinase per liter of batch culture were detected when cultivated in M9 medium containing casamino acids, L-tyrosine, and copper supplements. The black pigment, however, was not seen when grown in LB medium, suggesting that the trp promoter is well regulated. When recombinant E. coli cells grown in LB medium were transferred to a tryptophan-deficient minimal medium with phenol, we observed that phenol was removed from the solution, and the color of the medium turned black. This is due to the fact that the tyrosinase has polyphenol oxidase properties. We expect to use this recombinant E. coli for the waste treatment of phenolic compounds.

Standardisation and adaptation of the Denver Developmental Screening Test (DDST) and Denver II for use in Singapore children

OBJECTIVE

To modify and standardise the Denver Developmental Screening Test (DDST) and Denver II for developmental screening of children in Singapore.

METHOD

The study used a quota sample of 2,194 Singapore children aged 4 weeks to 6 years. Logistic regression analysis established the 25th, 50th, 75th, and 90th percentile passing age for achieving the test tasks. Subgroup differences in Sex, Ethnicity, Social Class and Mother's Education were analysed by stepwise logistic regression; the composite norms for items with statistically significant subgroup differences (p < or = 0.10), were then adjusted by weighting based on the composition of Singapore children. The study protocol was based on the DDST (1975) and Denver II (1990), the latest version of the DDST. Modifications were introduced to improve on the sensitivity of the test and to make the test more suited to Singapore culture.

MAIN FINDINGS

Out of the 215 items studied, 115 items were selected to form the new test, DDST, Singapore, DDST, Singapore shares 63% of the items with DDST (1975) and 67% of the items with Denver II. Among the comparable items, differences between the norms of Singapore and Denver children greater than 10% were demonstrated in more than 30 items, and differences of greater than 20% in 10 items. Within the study sample of Singapore children, there were relatively smaller differences among the subgroups studied. Only 10 items had clinically significant subgroup differences of more than 10%. None had more than 20% difference.

CONCLUSION

DDST, Singapore is substantially different from the DDST (1975) and Denver II (1990). The use of the local standardised version for developmental screening of Singapore children is justified.

Nitrazepam-induced cricopharyngeal dysphagia, abnormal esophageal peristalsis and associated bronchospasm: probable cause of nitrazepam-related sudden death

Nitrazepam was used in the treatment of resistant myoclonic epilepsy in 38 children. After the occurrence of nitrazepam-associated swallowing incoordination, high-peaked esophageal peristalsis and related bronchospasm in one patient, we initiated a prospective study of esophageal manometry using a station pull-through technique with a pediatric 4-channel continuous perfusing system. Three more patients were found to have delayed cricopharyngeal relaxation and high-peaked esophageal peristaltic waves. The initial patient developed severe respiratory distress and bronchospasm necessitating ventilatory support while on nitrazepam and improved dramatically with subsequent normal manometric study following nitrazepam discontinuation. Nitrazepam was reintroduced for its anticonvulsant and cognitive benefits and was tolerated at a reduced dosage. We postulate a central nervous system effect of nitrazepam promoting parasympathetic overactivity or vagotonia which can cause potentially fatal respiratory distress. Care must be exercised in nitrazepam use and esophageal manometry may be helpful in defining patients at greater risk for sudden death.

Hyperekplexia and sudden neonatal death

Fifteen patients with hyperekplexia were identified in 3 families; diagnostic clinical characteristics were defined which allowed for early recognition and treatment. During the first 24 hours of life, spontaneous apnea and sluggish feeding effort were observed. After the first 24 hours, surviving infants exhibited the hyperekplexic startle response to nose tapping. This startle response is characterized by sudden muscular rigidity, feeding-induced oropharyngeal incoordination, and poor air exchange often with apnea, persisting with repetitive nose tapping. Untreated infants experienced recurring apnea until 1 year of age. Three of 15 patients died unexpectedly during the neonatal period. Patients treated with clonazepam (0.1-0.2 mg/kg/day) had no serious apneic episodes and startle reflexes were diminished. The pathophysiologic mechanism for hyperekplexia remains obscure. Electroencephalographic studies were consistently normal. The response to and tolerance of benzodiazepines are striking in newborns and infants and suggest an aberrant central nervous system reflex as the etiology; therefore, hyperekplexia should be considered in the evaluation of neonates and infants with apnea, aspiration pneumonia, episodic muscular rigidity, hyperexcitability, and near-miss sudden infant death syndrome. The need for immediate monitoring of at-risk infants, observation for signs of hyperekplexia, and initiation of clonazepam in these patients are emphasized. Hyperekplexic startle response to nose tapping should be included in the routine examination of all newborns.

Theoretical analysis of the effect of cell recycling on recombinant cell fermentation processes

A cell recycle system is studied for two-stage continuous fermentation. Cell recycle around the second stage provides higher cell concentrations than processes without recycle and a longer residence time of the cell, which is necessary for inducible products, especially in recombinant cell fermentation. Residence time distribution of the cell in the fermentor is important for the optimization of inducible products. The residence time distributions are studied for the cases with and without significant cell growth in the second stage. With cell growth in the second stage, three cases are considered. These are the cases of (1) zero residence time for two daughter cells after the cell division, (2) zero residence time of one daughter cell after the cell division and inherited residence time for the other daughter cell from the mother cell after the cell division, and (3) two daughter cells having the residence time of the mother cell after the cell division.

Characterization of alpha-adrenoceptors in the nucleus reticularis gigantocellularis involved in the cardiovascular depressant effects of guanabenz in the rat

The participation of alpha-adrenoceptors in the nucleus reticularis gigantocellularis in the hypotensive, negative inotropic and chronotropic effects induced by guanabenz, was examined in rats anesthetized with pentobarbital sodium (40 mg/kg, i.p.). Pretreatment with alpha-adrenoceptor antagonists yohimbine (10 micrograms), phentolamine (2.5 micrograms) and phenoxybenzamine (20 micrograms), which were injected bilaterally into the nucleus reticularis gigantocellularis, significantly antagonized the cardiovascular suppressant effects normally produced by systemic administration of guanabenz (10 micrograms/kg, i.v.). Pretreatment with prazosin (0.25 microgram) did not affect the vasodepressive, but significantly attenuated the bradycardic actions of guanabenz. The general trend of "antagonization potency" shown by the alpha-adrenergic blockers, against the cardiovascular effects of guanabenz, was in the order: yohimbine greater than phentolamine greater than phenoxybenzamine greater than prazosin. It is concluded that while the alpha 2-adrenoceptors in the nucleus reticularis gigantocellularis are more critically involved in the antihypertensive actions of guanabenz, the possibility exists that alpha 1-adrenoceptors may also participate, in part.

Concomitant hypotensive and antinociceptive effects of guanabenz in conscious rats: involvement of nucleus reticularis gigantocellularis

Subcutaneous administration of guanabenz (1, 2, 5, or 8 mg/kg) in conscious Sprague-Dawley rats exerted concomitant suppressive actions on systolic pressure (tail-cuff sphygmomanometric measurement) and pain responses (hot-plate algesio-metric assay) that varied both in degree (antinociception much greater than hypotension) and response pattern. Furthermore, both depressive effects were appreciably attenuated by bilateral lesions of the nucleus reticularis gigantocellularis in the medulla oblongata. It is speculated that separate subpopulations of neurons within this reticular nucleus may be involved in the expression of hypotension and antinociception by this amino-guanidine derivative.

The roles of alpha 2-adrenoceptors in the nucleus reticularis gigantocellularis and vagal mechanism in the cardiovascular suppressive effects of guanabenz in the rat

In pentobarbital-anesthetized rats, pretreatment with yohimbine (10 micrograms), which was microinjected into the bilateral nucleus reticularis gigantocellularis (NRGC), significantly antagonized the reduction in arterial pressure, and the force and rate of heart contraction normally promoted by systemic administration of guanabenz (10 micrograms/kg, i.v.). At the same time, the vasodepressive as well as negative inotropic and chronotropic effects of direct application of guanabenz (500 ng) into the NRGC were attenuated by bilateral cervical vagotomy or atropine sulfate (1 mg/kg, i.v.). We conclude that guanabenz may promote antihypertension by activating the alpha 2-adrenoceptors in the NRGC, which in turn elicits cardiovascular suppression by at least facilitating the vagal outflows to the heart.

Pulmonary edema as a cause for fulminant death following microinjection of kainic acid into the rat medulla oblongata

The present study confirmed histopathologically the suggestion that pulmonary edema may underlie the fulminant death following microinjection of kainic acid into many medullary sites in rats anesthetized with pentobarbital sodium. We also observed a sustained elevation in systemic arterial pressure, cardiac contractility and heart rate before the animal succumbed to kainate neurotoxicity. It is suggested that the increased systemic hydrostatic pressure may retrogradely promote pulmonary hypertension that precipitates pulmonary edema.