Methylphenidate causes cytotoxicity on photoreceptor cells via autophagy

Methylphenidate (MPH) is used as the first-line treatment for attention-deficit hyperactivity disorder. However, there are concerns that this treatment may be associated with increased risk of retinal damage. This study was to investigate cytotoxicity of MPH on photoreceptor cells and explore its underlying mechanisms. MPH-caused cell toxicity was established in 661 W cells. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium-bromid and lactate dehydrogenase assays. Oxidative stress was measured by the markers: glutathione (GSH) reductase, catalase, and superoxide dismutase activities as well as GSH, reactive oxygen species, and malondialdehyde levels. Gene and protein expression was detected by real-time polymerase chain reaction (PCR) and western blot, respectively. Results showed that MPH decreased 661 W cell viability, increased caspase-3/9 activities, and induced oxidative stress. Furthermore, MPH treatment increased messenger RNA (mRNA) expression of Beclin-1 and microtubule-associated protein 1A/1B-light chain 3B (LC3B) protein expression in 661 W cells, suggesting autophagy was induced. MPH treatment also upregulated p-JAK1/p-STAT1 protein expression. These data demonstrated that MPH could increase oxidative stress in photoreceptor cells to cause cell toxicity via autophagy, providing the scientific rationale for the photoreceptor cell damage caused by the MPH administration.

Evaluation of the CareStart™ glucose-6-phosphate dehydrogenase (G6PD) rapid diagnostic test in the field settings and assessment of perceived risk from primaquine at the community level in Cambodia

Background

Primaquine is an approved radical cure treatment for Plasmodium vivax malaria but treatment can result in life-threatening hemolysis if given to a glucose-6-phosphate dehydrogenase deficient (G6PDd) patient. There is a need for reliable point-of-care G6PD diagnostic tests.

Objectives

To evaluate the performance of the CareStart™ rapid diagnostic test (RDT) in the hands of healthcare workers (HCWs) and village malaria workers (VMWs) in field settings, and to better understand user perceptions about the risks and benefits of PQ treatment guided by RDT results.

Methods

This study enrolled 105 HCWs and VMWs, herein referred to as trainees, who tested 1,543 healthy adult male volunteers from 84 villages in Cambodia. The trainees were instructed on G6PD screening, primaquine case management, and completed pre and post-training questionnaires. Each trainee tested up to 16 volunteers in the field under observation by the study staff.

Results

Out of 1,542 evaluable G6PD volunteers, 251 (16.28%) had quantitative enzymatic activity less than 30% of an adjusted male median (8.30 U/g Hb). There was no significant difference in test sensitivity in detecting G6PDd between trainees (97.21%), expert study staff in the field (98.01%), and in a laboratory setting (95.62%) (p = 0.229); however, test specificity was different for trainees (96.62%), expert study staff in the field (98.14%), and experts in the laboratory (98.99%) (p < 0.001). Negative predictive values were not statistically different for trainees, expert staff, and laboratory testing: 99.44%, 99.61%, and 99.15%, respectively. Knowledge scores increased significantly post-training, with 98.7% willing to prescribe primaquine for P.vivax malaria, an improvement from 40.6% pre-training (p < 0.001).

Conclusion

This study demonstrated ability of medical staff with different background to accurately use CareStart™ RDT to identify G6PDd in male patients, which may enable safer prescribing of primaquine; however, pharmacovigilance is required to address possible G6PDd misclassifications.

Atovaquone-Proguanil in Combination With Artesunate to Treat Multidrug-Resistant P. falciparum Malaria in Cambodia: An Open-Label Randomized Trial

Background

Recent artemisinin-combination therapy failures in Cambodia prompted a search for alternatives. Atovaquone-proguanil (AP), a safe, effective treatment for multidrug-resistant Plasmodium falciparum (P.f.), previously demonstrated additive effects in combination with artesunate (AS).

Methods

Patients with P.f. or mixed-species infection (n = 205) in Anlong Veng (AV; n = 157) and Kratie (KT; n = 48), Cambodia, were randomized open-label 1:1 to a fixed-dose 3-day AP regimen +/-3 days of co-administered artesunate (ASAP). Single low-dose primaquine (PQ, 15 mg) was given on day 1 to prevent gametocyte-mediated transmission.

Results

Polymerase chain reaction-adjusted adequate clinical and parasitological response at 42 days was 90% for AP (95% confidence interval [CI], 82%-95%) and 92% for ASAP (95% CI, 83%-96%; P = .73). The median parasite clearance time was 72 hours for ASAP in AV vs 56 hours in KT (P < .001) and was no different than AP alone. At 1 week postprimaquine, 7% of the ASAP group carried microscopic gametocytes vs 29% for AP alone (P = .0001). Nearly all P.f. isolates had C580Y K13 propeller artemisinin resistance mutations (AV 99%; KT 88%). Only 1 of 14 treatment failures carried the cytochrome bc1 (Pfcytb) atovaquone resistance mutation, which was not present at baseline. P.f. isolates remained atovaquone sensitive in vitro but cycloguanil resistant, with a triple P.f. dihydrofolate reductase mutation.

Conclusions

Atovaquone-proguanil remained marginally effective in Cambodia (≥90%) with minimal Pfcytb mutations observed. Treatment failures in the presence of ex vivo atovaquone sensitivity and adequate plasma levels may be attributable to cycloguanil and/or artemisinin resistance. Artesunate co-administration provided little additional blood-stage efficacy but reduced post-treatment gametocyte carriage in combination with AP beyond single low-dose primaquine.

Measuring ex vivo drug susceptibility in Plasmodium vivax isolates from Cambodia

Background

While intensive Plasmodium falciparum multidrug resistance surveillance continues in Cambodia, relatively little is known about Plasmodium vivax drug resistance in Cambodia or elsewhere. To investigate P. vivax anti-malarial susceptibility in Cambodia, 76 fresh P. vivax isolates collected from Oddar Meanchey (northern Cambodia) in 2013–2015 were assessed for ex vivo drug susceptibility using the microscopy-based schizont maturation test (SMT) and a Plasmodium pan-species lactate dehydrogenase (pLDH) ELISA. P. vivax multidrug resistance gene 1 (pvmdr1) mutations, and copy number were analysed in a subset of isolates.

Results

Ex vivo testing was interpretable in 80% of isolates using the pLDH-ELISA, but only 25% with the SMT. Plasmodium vivax drug susceptibility by pLDH-ELISA was directly compared with 58 P. falciparum isolates collected from the same locations in 2013–4, tested by histidine-rich protein-2 ELISA. Median pLDH-ELISA IC₅₀ of P. vivax isolates was significantly lower for dihydroartemisinin (3.4 vs 6.3 nM), artesunate (3.2 vs 5.7 nM), and chloroquine (22.1 vs 103.8 nM) than P. falciparum but higher for mefloquine (92 vs 66 nM). There were not significant differences for lumefantrine or doxycycline. Both P. vivax and P. falciparum had comparable median piperaquine IC₅₀ (106.5 vs 123.8 nM), but some P. falciparum isolates were able to grow in much higher concentrations above the normal standard range used, attaining up to 100-fold greater IC₅₀s than P. vivax. A high percentage of P. vivax isolates had pvmdr1 Y976F (78%) and F1076L (83%) mutations but none had pvmdr1 amplification.

Conclusion

The findings of high P. vivax IC₅₀ to mefloquine and piperaquine, but not chloroquine, suggest significant drug pressure from drugs used to treat multidrug resistant P. falciparum in Cambodia. Plasmodium vivax isolates are frequently exposed to mefloquine and piperaquine due to mixed infections and the long elimination half-life of these drugs. Difficulty distinguishing infection due to relapsing hypnozoites versus blood-stage recrudescence complicates clinical detection of P. vivax resistance, while well-validated molecular markers of chloroquine resistance remain elusive. The pLDH assay may be a useful adjunctive tool for monitoring for emerging drug resistance, though more thorough validation is needed. Given high grade clinical chloroquine resistance observed recently in neighbouring countries, low chloroquine IC₅₀ values seen here should not be interpreted as susceptibility in the absence of clinical data. Incorporating pLDH monitoring with therapeutic efficacy studies for individuals with P. vivax will help to further validate this field-expedient method.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-2034-2) contains supplementary material, which is available to authorized users.

Ex vivo piperaquine resistance developed rapidly in Plasmodium falciparum isolates in northern Cambodia compared to Thailand

Background

The recent dramatic decline in dihydroartemisinin-piperaquine (DHA-PPQ) efficacy in northwestern Cambodia has raised concerns about the rapid spread of piperaquine resistance just as DHA-PPQ is being introduced as first-line therapy in neighbouring countries.

Methods

Ex vivo parasite susceptibilities were tracked to determine the rate of progression of DHA, PPQ and mefloquine (MQ) resistance from sentinel sites on the Thai–Cambodian and Thai–Myanmar borders from 2010 to 2015. Immediate ex vivo (IEV) histidine-rich protein 2 (HRP-2) assays were used on fresh patient Plasmodium falciparum isolates to determine drug susceptibility profiles.

Results

IEV HRP-2 assays detected the precipitous emergence of PPQ resistance in Cambodia beginning in 2013 when 40 % of isolates had an IC₉₀ greater than the upper limit of prior years, and this rate doubled to 80 % by 2015. In contrast, Thai–Myanmar isolates from 2013 to 14 remained PPQ-sensitive, while northeastern Thai isolates appeared to have an intermediate resistance profile. The opposite trend was observed for MQ where Cambodian isolates appeared to have a modest increase in overall sensitivity during the same period, with IC₅₀ declining to median levels comparable to those found in Thailand. A significant association between increased PPQ IC₅₀ and IC₉₀ among Cambodian isolates with DHA-PPQ treatment failure was observed. Nearly all Cambodian and Thai isolates were deemed artemisinin resistant with a >1 % survival rate for DHA in the ring-stage assay (RSA), though there was no correlation among isolates to indicate cross-resistance between PPQ and artemisinins.

Conclusions

Clinical DHA-PPQ failures appear to be associated with declines in the long-acting partner drug PPQ, though sensitivity appears to remain largely intact for now in western Thailand. Rapid progression of PPQ resistance associated with DHA-PPQ treatment failures in northern Cambodia limits drugs of choice in this region, and urgently requires alternative therapy. The temporary re-introduction of artesunate AS-MQ is the current response to PPQ resistance in this area, due to inverse MQ and PPQ resistance patterns. This will require careful monitoring for re-emergence of MQ resistance, and possible simultaneous resistance to all three drugs (AS, MQ and PPQ).

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1569-y) contains supplementary material, which is available to authorized users.

Predicting 30-day Hospital Readmission with Publicly Available Administrative Database. A Conditional Logistic Regression Modeling Approach

INTRODUCTION

This article is part of the Focus Theme of Methods of Information in Medicine on "Big Data and Analytics in Healthcare".

BACKGROUND

Hospital readmissions raise healthcare costs and cause significant distress to providers and patients. It is, therefore, of great interest to healthcare organizations to predict what patients are at risk to be readmitted to their hospitals. However, current logistic regression based risk prediction models have limited prediction power when applied to hospital administrative data. Meanwhile, although decision trees and random forests have been applied, they tend to be too complex to understand among the hospital practitioners.

OBJECTIVES

Explore the use of conditional logistic regression to increase the prediction accuracy.

METHODS

We analyzed an HCUP statewide inpatient discharge record dataset, which includes patient demographics, clinical and care utilization data from California. We extracted records of heart failure Medicare beneficiaries who had inpatient experience during an 11-month period. We corrected the data imbalance issue with under-sampling. In our study, we first applied standard logistic regression and decision tree to obtain influential variables and derive practically meaning decision rules. We then stratified the original data set accordingly and applied logistic regression on each data stratum. We further explored the effect of interacting variables in the logistic regression modeling. We conducted cross validation to assess the overall prediction performance of conditional logistic regression (CLR) and compared it with standard classification models.

RESULTS

The developed CLR models outperformed several standard classification models (e.g., straightforward logistic regression, stepwise logistic regression, random forest, support vector machine). For example, the best CLR model improved the classification accuracy by nearly 20% over the straightforward logistic regression model. Furthermore, the developed CLR models tend to achieve better sensitivity of more than 10% over the standard classification models, which can be translated to correct labeling of additional 400 - 500 readmissions for heart failure patients in the state of California over a year. Lastly, several key predictor identified from the HCUP data include the disposition location from discharge, the number of chronic conditions, and the number of acute procedures.

CONCLUSIONS

It would be beneficial to apply simple decision rules obtained from the decision tree in an ad-hoc manner to guide the cohort stratification. It could be potentially beneficial to explore the effect of pairwise interactions between influential predictors when building the logistic regression models for different data strata. Judicious use of the ad-hoc CLR models developed offers insights into future development of prediction models for hospital readmissions, which can lead to better intuition in identifying high-risk patients and developing effective post-discharge care strategies. Lastly, this paper is expected to raise the awareness of collecting data on additional markers and developing necessary database infrastructure for larger-scale exploratory studies on readmission risk prediction.

Dihydroartemisinin-piperaquine failure associated with a triple mutant including kelch13 C580Y in Cambodia: an observational cohort study

BACKGROUND

Dihydroartemisinin-piperaquine has been adopted as first-line artemisinin combination therapy (ACT) for multidrug-resistant Plasmodium falciparum malaria in Cambodia because of few remaining alternatives. We aimed to assess the efficacy of standard 3 day dihydroartemisinin-piperaquine treatment of uncomplicated P falciparum malaria, with and without the addition of primaquine, focusing on the factors involved in drug resistance.

METHODS

In this observational cohort study, we assessed 107 adults aged 18-65 years presenting to Anlong Veng District Hospital, Oddar Meanchey Province, Cambodia, with uncomplicated P falciparum or mixed P falciparum/Plasmodium vivax infection of between 1000 and 200,000 parasites per μL of blood, and participating in a randomised clinical trial in which all had received dihydroartemisinin-piperaquine for 3 days, after which they had been randomly allocated to receive either primaquine or no primaquine. The trial was halted early due to poor dihydroartemisinin-piperaquine efficacy, and we assessed day 42 PCR-corrected therapeutic efficacy (proportion of patients with recurrence at 42 days) and evidence of drug resistance from the initial cohort. We did analyses on both the intention to treat (ITT), modified ITT (withdrawals, losses to follow-up, and those with secondary outcomes [eg, new non-recrudescent malaria infection] were censored on the last day of follow-up), and per-protocol populations of the original trial. The original trial was registered with ClinicalTrials.gov, number NCT01280162.

FINDINGS

Between Dec 10, 2012, and Feb 18, 2014, we had enrolled 107 patients in the original trial. Enrolment was voluntarily halted on Feb 16, 2014, before reaching planned enrolment (n=150) because of poor efficacy. We had randomly allocated 50 patients to primaquine and 51 patients to no primaquine groups. PCR-adjusted Kaplan-Meier risk of P falciparum 42 day recrudescence was 54% (95% CI 45-63) in the modified ITT analysis population. We found two kelch13 propeller gene mutations associated with artemisinin resistance--a non-synonymous Cys580Tyr substitution in 70 (65%) of 107 participants, an Arg539Thr substitution in 33 (31%), and a wild-type parasite in four (4%). Unlike Arg539Thr, Cys580Tyr was accompanied by two other mutations associated with extended parasite clearance (MAL10:688956 and MAL13:1718319). This combination triple mutation was associated with a 5·4 times greater risk of treatment failure (hazard ratio 5·4 [95% CI 2·4-12]; p<0·0001) and higher piperaquine 50% inhibitory concentration (triple mutant 34 nM [28-41]; non-triple mutant 24 nM [1-27]; p=0·003) than other infections had. The drug was well tolerated, with gastrointestinal symptoms being the most common complaints.

INTERPRETATION

The dramatic decline in efficacy of dihydroartemisinin-piperaquine compared with what was observed in a study at the same location in 2010 was strongly associated with a new triple mutation including the kelch13 Cys580Tyr substitution. 3 days of artemisinin as part of an artemisinin combination therapy regimen might be insufficient. Strict regulation and monitoring of antimalarial use, along with non-pharmacological approaches to malaria resistance containment, must be integral parts of the public health response to rapidly accelerating drug resistance in the region.

FUNDING

Armed Forces Health Surveillance Center/Global Emerging Infections Surveillance and Response System, Military Infectious Disease Research Program, National Institute of Allergy and Infectious Diseases, and American Society of Tropical Medicine and Hygiene/Burroughs Wellcome Fund.

Blackwater fever in an uncomplicated Plasmodium falciparum patient treated with dihydroartemisinin-piperaquine

The mechanism of massive intravascular haemolysis occurring during the treatment of malaria infection resulting in haemoglobinuria, commonly known as blackwater fever (BWF), remains unknown. BWF is most often seen in those with severe malaria treated with amino-alcohol drugs, including quinine, mefloquine and halofantrine. The potential for drugs containing artemisinins, chloroquine or piperaquine to cause oxidant haemolysis is believed to be much lower, particularly during treatment of uncomplicated malaria. Here is an unusual case of BWF, which developed on day 2 of treatment for uncomplicated Plasmodium falciparum infection with dihydroartemisinin-piperaquine (DHA-PIP) with documented evidence of concomitant seropositivity for Chikungunya infection.

Autophagy and chemotherapy resistance: a promising therapeutic target for cancer treatment

Induction of cell death and inhibition of cell survival are the main principles of cancer therapy. Resistance to chemotherapeutic agents is a major problem in oncology, which limits the effectiveness of anticancer drugs. A variety of factors contribute to drug resistance, including host factors, specific genetic or epigenetic alterations in the cancer cells and so on. Although various mechanisms by which cancer cells become resistant to anticancer drugs in the microenvironment have been well elucidated, how to circumvent this resistance to improve anticancer efficacy remains to be defined. Autophagy, an important homeostatic cellular recycling mechanism, is now emerging as a crucial player in response to metabolic and therapeutic stresses, which attempts to maintain/restore metabolic homeostasis through the catabolic lysis of excessive or unnecessary proteins and injured or aged organelles. Recently, several studies have shown that autophagy constitutes a potential target for cancer therapy and the induction of autophagy in response to therapeutics can be viewed as having a prodeath or a prosurvival role, which contributes to the anticancer efficacy of these drugs as well as drug resistance. Thus, understanding the novel function of autophagy may allow us to develop a promising therapeutic strategy to enhance the effects of chemotherapy and improve clinical outcomes in the treatment of cancer patients.

Graphical Overlays: Using Layered Elements to Aid Chart Reading

Reading a visualization can involve a number of tasks such as extracting, comparing or aggregating numerical values. Yet, most of the charts that are published in newspapers, reports, books, and on the Web only support a subset of these tasks. In this paper we introduce graphical overlays-visual elements that are layered onto charts to facilitate a larger set of chart reading tasks. These overlays directly support the lower-level perceptual and cognitive processes that viewers must perform to read a chart. We identify five main types of overlays that support these processes; the overlays can provide (1) reference structures such as gridlines, (2) highlights such as outlines around important marks, (3) redundant encodings such as numerical data labels, (4) summary statistics such as the mean or max and (5) annotations such as descriptive text for context. We then present an automated system that applies user-chosen graphical overlays to existing chart bitmaps. Our approach is based on the insight that generating most of these graphical overlays only requires knowing the properties of the visual marks and axes that encode the data, but does not require access to the underlying data values. Thus, our system analyzes the chart bitmap to extract only the properties necessary to generate the desired overlay. We also discuss techniques for generating interactive overlays that provide additional controls to viewers. We demonstrate several examples of each overlay type for bar, pie and line charts.

High-resolution melting analysis for the rapid detection of an intronic single nucleotide polymorphism in SLC22A12 in male patients with primary gout in China

OBJECTIVES

The human urate transporter 1 (URAT1, encoded by SLC22A12) was recently identified as the major absorptive urate transporter protein in the kidney responsible for regulating blood urate levels. The present study was designed to investigate the rs893006 polymorphism (GG, GT, and TT) in SLC22A12 in a total of 292 Chinese male subjects. Differences of clinical characteristics among the genotype groups were analysed.

METHODS

A total of 124 consecutive patients with diagnosis of primary gout and 168 healthy male volunteers were enrolled in this study. Demographic and clinical data were obtained from the patients and controls. DNA was purified from peripheral blood and the rs893006 polymorphism was determined with sequencing analysis. In addition, DNA samples were detected by high-resolution melting (HRM) analysis. Melting curves were analysed as fluorescence difference plots. The shift and curve shapes of melting profiles were used to distinguish the different genotypes.

RESULTS

GG, GT, and TT genotypes were unambiguously distinguished with HRM technology. Genotyping based on HRM analysis was fully concordant with the sequencing. Serum uric acid levels in the TT genotype subjects were significantly lower than those in the GG and GT genotypes. However, no differences among the groups were found in body mass index (BMI), blood pressure, creatinine, total cholesterol, and triglycerides. The TT genotype was observed more frequently among the low uric acid group than the high uric acid group.

CONCLUSIONS

HRM analysis is a simple, rapid and accurate one-tube assay for genotyping the SLCSSA12 gene. The rs893006 polymorphism in SLC22CA12 was confirmed to be a genetic risk for hyperuricaemia among the Chinese male population.

Synthesis and monoamine transporter affinity of 3beta-(4-(2-pyrrolyl)phenyl)-8-azabicycl

3Beta-(5-indolyl)-8-azabicyclo[3.2.1]octanes display potent binding affinity for both the dopamine and serotonin transporters, while certain 3beta-(4-(2-pyrrolyl)phenyl)-8-azabicyclo[3.2.1]octanes selectively bind to the serotonin transporter.

What is the role of between meal snacks with intensive basal bolus regimens using preprandial lispro?

AIMS

Hypoglycaemia avoidance for patients on intensive insulin regimens requires the eating of snacks between meals. Insulin lispro with its shorter action profile may permit omitting such snacks.

METHODS

Ten Type 1 diabetes mellitus (DM) patients were rendered euglycaemic with a morning intravenous insulin infusion. Each was studied on six afternoons in random order, with previously determined equal doses of Humulin S (HS) injected at -30min, or lispro injected at 0 min before a standard lunch. The snack was either eaten mid-afternoon, combined with the lunch or omitted altogether.

RESULTS

Lispro and lunch with a snack combined at 0 min gave equal control to HS at -30 min and lunch at 0 min with a mid-afternoon snack. Lispro and lunch at 0 min with a mid-afternoon snack gave a lower early postprandial glucose. At 120 min glucose (mean mmol/l +/- SEM) were 7.4+/-0.8 vs. 7.0+/-1.0 (P = 1.0) and 3.9+/-0.5 (P = 0.045), respectively. The area under the insulin curve over the whole afternoon was similar for HS and lispro (13193.3+/-974.6 vs. 13193.6+/-809.9 mIU/min, P = 1.0) but with a greater peak for lispro than HS with lispro falling more rapidly. Despite significantly lower lispro levels after 180 min, intermediary metabolites concentrations were similar in all HS and lispro study days.

CONCLUSIONS

Lispro injected immediately before combined snack and lunch and with no subsequent snack achieves equivalent control to conventional regimens using HS -30 min before lunch and mid-afternoon snack. Lispro taken with traditional meal patterns without dose reduction risks early postprandial hypoglycaemia and late hyperglycaemia.

Vancomycin administration in continuous ambulatory peritoneal dialysis: the risk of ototoxicity

A prospective study was undertaken in 16 patients with chronic renal failure on continuous ambulatory peritoneal dialysis, with 22 episodes of peritonitis treated with vancomycin, a known ototoxic agent. Twelve patients had one episode each, and four had recurrent peritonitis. Each treatment course consisted of two infusions of vancomycin (30 mg/kg body weight) in 2 L of peritoneal dialysate administered at 6-day intervals. Serum vancomycin analyzed by enzyme immunoassay showed a mean trough level of 11.00 microg/ml on day 6 and mean serum levels of 33.8 and 38.6 microg/ml about 12 hours after administration on days 1 and 7, respectively. Similar levels, well within the therapeutic range, were encountered with repeated vancomycin therapy for recurrent episodes of peritonitis, suggesting that no changes occurred in the pharmacokinetic profile of the drug. Pure-tone audiometry, electronystagmography, and clinical assessment performed during each course of treatment showed no evidence of ototoxicity even on repeated courses of vancomycin therapy. The results suggest that vancomycin therapy when given in appropriate concentrations as a single therapeutic agent is both effective and safe. We believe, however, that vancomycin administered in combination with an aminoglycoside may produce ototoxic effects that may be greatly aggravated, possibly because of synergism.

Instant electronic imaging systems are superior to Polaroid at detecting sight-threatening diabetic retinopathy

Polaroid photography in diabetic retinopathy screening allows instant image availability to enhance the results of ophthalmoscopy. Retinal cameras are now being developed which use video/digital imaging techniques to produce an instant enlarged retinal image on a computer monitor screen. We aimed to compare one such electronic imaging system, attached to a Canon CR5 45NM, with standard Polaroid retinal photography. Two hundred and thirteen eyes from 107 diabetic patients were photographed through dilated pupils by both systems in random order and the images were analysed blind. Diabetic retinopathy was present in 58 eyes of which 55/58 (95%) were detected on the electronic image and only 49/58 (84%) on the Polaroid. Of 34 eyes requiring ophthalmologist referral according to standard European criteria, 34/34 (100%) were detected on the electronic image and only 24/34 (71%) on the Polaroid. Side by side comparisons showed electronic imaging to be superior to Polaroid at lesion detection. Using linear analogue scales, the patients assessed the electronic imaging photographic flash as less uncomfortable than the Polaroid equivalent (p < 0.0001). Other advantages of electronic imaging include: ready storage of the images with other patient clinical data on the diabetes computerized register/database; potential for image enhancement and analysis using image analysis software and electronic transfer of images to ophthalmologist or general practitioner. Electronic imaging systems represent a potential major advance for the improvement of diabetic retinopathy screening.

Potential antidepressant effects of novel tropane compounds, selective for serotonin or dopamine transporters

The forced swimming test (FST) predicts the efficacy of clinically effective antidepressants. In the present study, using the FST we examined the antidepressant potential of three novel tropane analogs: 8-methyl-2beta-propanoyl-3beta-(4-(1-methylethyl)phenyl)-8-azabicy clo[3.2.1] (WF-31) and 2beta-propanoyl-3beta-(4-(1-methylethyl)phenyl)-8-azabicyclo[3.2.1 ]octane (WF-50), selective inhibitors of serotonin uptake, and 8-methyl-2beta-propanoyl-3beta-(4-(1-methylphenyl)-8-azabicyclo[3. 2.1] octane (PTT, WF-11), a selective inhibitor of dopamine uptake. Fluoxetine and GBR 12909 were used as controls for selective inhibitors of serotonin and dopamine, respectively. Drugs were administered three times in a 24-hr period between pretest and test sessions. Intraperitoneal administration of WF-31 (0.1-10.0 mg/kg), WF-50 (0.3-10.0 mg/kg) and fluoxetine (0.3-10.0 mg/kg) dose-dependently decreased immobility while increasing swimming. In contrast, WF-11 (0.3-3.0 mg/kg) dose-dependently decreased immobility and increased both swimming and climbing, whereas GBR 12909 (3.0-30.0 mg/kg) decreased immobility, increased climbing but did not affect swimming. In a separate experiment, WF-11 (1.0 mg/kg) increased locomotor activity, whereas a higher dose of WF-11 (3.0 mg/kg) and GBR-12909 (30.0 mg/kg) produced stereotypic behaviors, suggesting that the effects in the FST may have been attributable to increases in general activity. However, the effects of WF-11 on swimming in the FST indicate that WF-11 produces antidepressant-like effects in addition to motor stimulation. These results confirm previous results that behavioral patterns manifested in the FST are characteristic of specific monoamine uptake inhibitors. In addition, these results demonstrate that WF-31 and WF-50 produce behavioral patterns similar to fluoxetine in the FST without accompanying decreases in motor activity, suggesting a potential antidepressant action. Based on comparisons with fluoxetine, the data suggest WF-31 and WF-50 may be therapeutically useful as potential antidepressant medications.

Psychiatric disorder in Malaysians with systemic lupus erythematosus

All 79 patients who attended a University Systemic Lupus Erythematosus (SLE) Clinic over a 6 month period were assessed using the Clinical Interview Schedule for psychiatric disorder. Using the ICD-9 Classification, 40 were found to have psychiatric disorder, 26 having depressive neurosis, six anxiety neurosis, five endogenous depression and three dementia. The group with psychiatric disorder had significantly poor family support as well as lack of a confidant compared to the group without psychiatric disorder (P < 0.01). There was no difference between the group with psychiatric disorder and those without psychiatric disorder in terms of age, duration of illness, ethnicity and severity of SLE. Psychiatric disorder is common affecting more than half the subjects and depression was the most frequent diagnosis.

The secretory pathway is normal in dithiothreitol-treated cells, but disulfide-bonded proteins are reduced and reversibly retained in the endoplasmic reticulum

Addition of 2 mM dithiothreitol (DTT) to HepG2 human hepatoma cells blocks secretion of newly made albumin and causes it to accumulate in the endoplasmic reticulum in the reduced state. Subsequent incubation of the cells in the absence of DTT allows the reduced albumin to form apparently normal disulfide bonds and to be secreted normally. Similarly, DTT treatment causes all newly made subunits of the H1 subunit of the asialoglycoprotein receptor to be retained in the endoplasmic reticulum in the reduced state; following removal of DTT H1 subunits form disulfide bonds via a normal endoplasmic reticulum folding intermediate and mature to the Golgi. Thus, apparently normal formation of disulfide bonds on these two proteins can occur post-translationally, as has been shown previously for the influenza HA hemagglutinin (Braakman, I., Helenius, J., and Helenius, A. (1992) EMBO J. 11, 1717-1722; Braakman, I., Helenius, J., and Helenius, A. (1992) Nature 356, 260-262). alpha 1-Antitrypsin contains no disulfide bonds; in the continuous presence of DTT it acquires a normal complement of complex oligosaccharides and is secreted at an only slightly reduced rate. Thus, the secretory pathway functions efficiently even when it is reduced by DTT. Endoplasmic reticulum retention of albumin and H1 during treatment with DTT presumably occurs because, without disulfide bonds, these proteins cannot fold properly, not because of any defect in the overall processes of vesicular transport and protein secretion.

Gentamicin ototoxicity in continuous ambulatory peritoneal dialysis

A prospective study was undertaken of 10 chronic renal failure patients on Continuous Ambulatory Peritoneal Dialysis (CAPD) complicated by repeated bouts of peritonitis treated with gentamicin. Each 10-day treatment course consisted of a 120 mg loading dose, followed by 16 mg in 21 of peritoneal dialysate, given four times a day. Serum gentamicin analysed by enzyme immunoassay showed a mean level of 5.2 micrograms/ml, (range 3.7 to 6.6 mg/ml) four hours after the loading dose. Similar levels, well within the therapeutic range, were maintained on the 3rd, 5th, 7th and 9th days of intraperitoneal gentamicin therapy, suggesting no accumulation of gentamicin in the serum. Pure tone audiometry, electronystagmography and clinical assessment were performed during each course of treatment. Although no evidence of ototoxicity was found during the first two courses of gentamicin, but disequilibrium and bobbing oscillopsia were present during the third and fourth courses of gentamicin. These findings could be explained by cumulative injury to the vestibular apparatus caused by repeated therapeutic insults.

Calcium is required for folding of newly made subunits of the asialoglycoprotein receptor within the endoplasmic reticulum

By resolving immunoprecipitates on nonreducing sodium dodecyl sulfate gels, we have detected several disulfide-bonded intermediates in folding within the endoplasmic reticulum of newly made H1 subunits of the asialoglycoprotein receptor. H1 in the endoplasmic reticulum (ER) can be partially unfolded by treatment of cells with dithiothreitol, but H1 in Golgi or post-Golgi organelles is resistant to such unfolding. This defines a late step in H1 folding that occurs just prior to exit from the ER. Depletion of calcium from the endoplasmic reticulum, either by treatment with A23187 or thapsigargin, has no effect on folding or secretion of newly made albumin, but totally blocks H1 maturation from the ER. No ER intermediates in H1 folding are formed in cells treated with A23187 or thapsigargin, indicating that at least an early step in H1 folding requires a high Ca2+ concentration in the ER lumen. As judged by cross-linking experiments, formation of H1 dimers and trimers occurs immediately after biosynthesis of the peptide chain, before monomer folding, and occurs normally in cells in which ER Ca2+ is reduced and where the monomer never folds properly. Calcium is essential for the asialoglycoprotein receptor to bind galactose, and our results suggest that Ca2+ is also essential for the receptor polypeptides to fold in the ER.

Cyclosporin A inhibits an initial step in folding of transferrin within the endoplasmic reticulum

As resolved by electrophoresis in non-reducing SDS gels, transferrin newly made in Hep G2 cells migrates as a very diffuse set of species. During a subsequent 1-h chase all transferrin polypeptides are converted to a single, rapidly migrating species. These changes in gel mobility are due to alterations in the pattern of disulfide bonding, are not caused by carbohydrate processing, and occur while the protein is in the rough endoplasmic reticulum. Cyclosporin A causes an approximately 10-min lag in transferrin folding, after which folding resumes at the normal rate. Cyclosporin A also retards transferrin maturation from the endoplasmic reticulum and its secretion, at concentrations that do not affect secretion of other hepatoma proteins. Neither FK506 nor rapamycin affect transferrin folding. We conclude that an initial stage in transferrin folding is accelerated by an endoplasmic reticulum peptidyl-proline isomerase that is inhibited by cyclosporin A.

Asymptomatic proteinuria and/or haematuria in 265 Malaysian adults

Two-hundred and sixty-five patients with asymptomatic proteinuria and/or haematuria were studied at the Department of Medicine, Universiti Kebangsaan Malaysia and Department of Nephrology, General Hospital Kuala Lumpur. They represented 25.4% of all the renal biopsies performed during the period 1980-88. All the three races were affected with 71.3% occurring between the ages of 20-39 years and 41.1% were detected during routine medical examination. Excluding those patients with lupus nephritis, IgA nephropathy was the commonest histological diagnosis (51.7%). The presence of severe and advanced histological changes in a significant number of biopsies emphasises the need for more effective screening and early referral of this group of patients.

IgA nephropathy in Malaysia

A total of 164 patients with IgA nephropathy were diagnosed at the Department of Medicine, Universiti Kebangsaan Malaysia and the Department of Nephrology, General Hospital, Kuala Lumpur between 1981-1988. This represented an incidence of 20.1% of all primary glomerulopathies seen in both units. The 3 major ethnic groups were equally affected with 59.7% occurring between the ages of 20-36 years. It was not uncommon in females. The high prevalence of hypertension, renal failure, heavy proteinuria at presentation and the increased chronicity index in the biopsy, suggest that IgA nephropathy is progressive disease leading to chronic renal failure.

Perturbation of cellular calcium blocks exit of secretory proteins from the rough endoplasmic reticulum

In the cultured human hepatoma HepG2, Ca2+ ionophores block secretion of different secretary proteins to different extents, alpha 1-antitrypsin secretion being more sensitive to A23187 and ionomycin than is alpha 1-antichymotrypsin, and albumin secretion the least of the three proteins studied. As judged by subcellular fractionation experiments and by treatment of pulse chase labeled protein with endoglycosidase H, A23187 and ionomycin cause newly made secretory proteins to remain within the rough endoplasmic reticulum (ER). Experiments in which A23187 is added at different times during a pulse or chase show that secretion of newly made alpha 1-antitrypsin becomes resistant to the ionophore, on average, 15 min after synthesis; this is about 20 min before it reaches the trans-Golgi, and while it is still within the rough ER. We speculate that a high concentration of Ca2+ within the ER may be essential for certain secretory proteins to fold properly, that folding is inhibited when ER Ca2+ levels are lowered by ionophore treatment, and that unfolded proteins, particularly alpha 1-antitrypsin, cannot exit the rough ER. Treatment of murine 3T3 fibroblasts or human hepatoma HepG2 cells with the Ca2+ ionophores A23187 or ionomycin also induces a severalfold accumulation of the ER lumenal protein Bip (Grp78). These findings disagree with a recent report that Ca2+ ionophores cause secretion of Bip and other resident ER proteins, but is consistent with other reports that A23187 causes accumulation of mRNAs for Bip and other ER lumenal proteins.

A vesicular intermediate in the transport of hepatoma secretory proteins from the rough endoplasmic reticulum to the Golgi complex

We have identified a vesicle fraction that contains alpha 1-antitrypsin and other human HepG2 hepatoma secretory proteins en route from the rough endoplasmic reticulum (RER) to the cis face of the Golgi complex. [35S]Methionine pulse-labeled cells were chased for various periods of time, and then a postnuclear supernatant fraction was resolved on a shallow sucrose-D2O gradient. This intermediate fraction has a density lighter than RER or Golgi vesicles. Most alpha 1-antitrypsin in this fraction (P1) bears N-linked oligosaccharides of composition similar to that of alpha 1-antitrypsin within the RER; mainly Man8GlcNac2 with lesser amounts of Man7GlcNac2 and Man9GlcNac2; this suggests that the protein has not yet reacted with alpha-mannosidase-I on the cis face of the Golgi complex. This light vesicle species is the first post-ER fraction to be filled by labeled alpha 1-antitrypsin after a short chase, and newly made secretory proteins enter this compartment in proportion to their rate of exit from the RER and their rate of secretion from the cells: alpha 1-antitrypsin and albumin faster than preC3 and alpha 1-antichymotrypsin, faster, in turn, then transferrin. Deoxynojirimycin, a drug that blocks removal of glucose residues from alpha 1-antitrypsin in the RER and blocks its intracellular maturation, also blocks its appearance in this intermediate compartment. Upon further chase of the cells, we detect sequential maturation of alpha 1-antitrypsin to two other intracellular forms: first, P2, a form that has the same gel mobility as P1 but that bears an endoglycosidase H-resistant oligosaccharide and is found in a compartment--probably the medial Golgi complex--of density higher than that of the intermediate that contains P1; and second, the mature sialylated form of alpha 1-antitrypsin.

Glucose removal from N-linked oligosaccharides is required for efficient maturation of certain secretory glycoproteins from the rough endoplasmic reticulum to the Golgi complex

1- Deoxynojirimycin is a specific inhibitor of glucosidases I and II, the first enzymes that process N-linked oligosaccharides after their transfer to polypeptides in the rough endoplasmic reticulum. In a pulse-chase experiment, 1- deoxynojirimycin greatly reduced the rate of secretion of alpha 1-antitrypsin and alpha 1-antichymotrypsin by human hepatoma HepG2 cells, but had marginal effects on secretion of the glycoproteins C3 and transferrin, or of albumin. As judged by equilibrium gradient centrifugation, 1- deoxynojirimycin caused alpha 1-antitrypsin and alpha 1-antichymotrypsin to accumulate in the rough endoplasmic reticulum. The oligosaccharides on cell-associated alpha 1-antitrypsin and alpha 1-antichymotrypsin synthesized in the presence of 1- deoxynojirimycin , remained sensitive to Endoglycosidase H and most likely had the structure Glu1- 3Man9GlcNAc2 . Tunicamycin, an antibiotic that inhibits addition of N-linked oligosaccharide units to glycoproteins, had a similar differential effect on secretion of these proteins. Swainsonine , an inhibitor of the Golgi enzyme alpha-mannosidase II, had no effect on the rates of protein secretion, although the proteins were in this case secreted with an abnormal N-linked, partially complex, oligosaccharide. We conclude that the movement of alpha 1-antitrypsin and alpha 1-antichymotrypsin from the rough endoplasmic reticulum to the Golgi requires that the N-linked oligosaccharides be processed to at least the Man9GlcNAc2 form; possibly this oligosaccharide forms part of the recognition site of a transport receptor for certain secretory proteins.

Blastogenic response of human lymphocytes to early antigen(s) of human cytomegalovirus

The lymphocytes of asymptomatic, seropositive donors demonstrated blastogenic responses to early antigens of human cytomegalovirus whether or not antibodies to early antigens were detectable. The lymphocytes of six of nine patients with active cytomegalovirus infections gave stimulation indexes of greater than or equal to 2.00 with antigens of productively infected cells, whereas only two patients demonstrated comparable stimulation indexes with early antigens. Four patients with stimulation indexes of greater than or equal to 2.00 to productively infected antigens had stimulation indexes of less than or equal to 2.00 to early antigens. Viral polypeptides with molecular weights of 83,000, 72,000, 62,000, 56,000, and 40,000 were identified in early antigen preparations.

Hepatoma secretory proteins migrate from rough endoplasmic reticulum to Golgi at characteristic rates

In eukaryotic cells, secretory proteins and glycoproteins migrate from the rough endoplasmic reticulum, their site of synthesis, through Golgi vesicles before being released from the cell. Cellular and viral integral plasma membrane glycoproteins are co-translationally inserted into the rough endoplasmic reticulum membrane and follow a similar pathway to the cell surface. Previous studies using endoglycosidase H (Endo H) suggested that in rat hepatoma cells the vesicular stomatitis virus (VSV) G protein, albumin and transferrin migrate from the rough endoplasmic reticulum to the Golgi apparatus at different rates. Here we show directly that in human hepatoma HepG2 cells, five secreted proteins mature from the rough endoplasmic reticulum to Golgi vesicles at characteristic rates which differ at least threefold. The results are incompatible with bulk-phase movement of the luminal contents of the endoplasmic reticulum, and suggest that there is a membrane-bound receptor that selectively mediates the transport of secretory proteins from the rough endoplasmic reticulum to the Golgi.

Reversible block in intracellular transport and budding of mutant vesicular stomatitis virus glycoproteins

The blocks in intracellular maturation of glycoprotein (G protein) synthesized by two temperature-sensitive vesicular stomatite's virus (VSV) mutants are reversible. Our earlier work demonstrated that at 40 degrees, the nonpermissive temperature, mutant ts L513(V) G protein accumulates in the rough endoplasmic reticulum. Here we show that when the temperature is lowered the high-mannose oligosaccharides on a significant fraction of ts L513(V) G protein, synthesized at 40 degrees, will be modified to the complex type. Moreover, when the temperature is lowered ts L513(V) G protein accumulated at 40 degrees will mature to the cell surface, as evidenced by its accessibility to extracellular trinitrobenzene sulfonate, and into virions. G protein synthesized at 40 degrees in ts L511(V)-infected cells undergoes most of the processing events characteristic of the Golgi complex. Although we reported previously that no ts L511(V) G protein reaches the plasma membrane at 40 degrees, we now find, using more sensitive techniques, that an appreciable fraction does reach the cell surface. ts L511(V) G protein is lost from the cells but is not incorporated into virions. However, an appreciable fraction of the ts L511(V) G protein which accumulates in cells at 40 degrees will mature into virions when the temperature is lowered. These results exclude irreversible denaturation of mutant G proteins as a cause of the block in intracellular maturation and virus budding.

Computer-produced holograms for scanners utilizing an auxiliary reflector

Computer-produced holograms for scanners utilizing an auxiliary reflector have been constructed and demonstrated. Mathematic formalism for the calculation and detailed fabrication procedures are described. This method can be used for producing holograms for operation at any wavelengths whenever direct recording is not practical or inconvenient. This method is particularly suitable for producing holograms for 2-D scanners in the longer wavelengths, such as ir, far ir, mm, microwave, and ultrasonic waves. Simplicity in operation of the 2-D scanner will make real-tme imaging systems practical in the long-wavelength region.