Deep learning-assisted diagnosis of parotid gland tumors by using contrast-enhanced CT imaging

OBJECTIVES

Imaging interpretation of the benignancy or malignancy of parotid gland tumors (PGTs) is a critical consideration prior to surgery in view of therapeutic and prognostic values of such discrimination. This study investigates the application of a deep learning-based method for preoperative stratification of PGTs.

MATERIALS AND METHODS

Using the 3D DenseNet-121 architecture and a dataset consisting of 117 volumetric arterial-phase contrast-enhanced CT scans, we developed a binary classifier for PGT distinction and tested it. We compared the discriminative performance of the model on the test set to that of 12 junior and 12 senior head and neck clinicians. Besides, potential clinical utility of the model was evaluated by measuring changes in unassisted and model-assisted performance of junior clinicians.

RESULTS

The model finally reached the sensitivity, specificity, PPV, NPV, F1-score of 0.955 (95% CI 0.751-0.998), 0.667 (95% CI 0.241-0.940), 0.913 (95% CI 0.705-0.985), 0.800 (95% CI 0.299-0.989) and 0.933, respectively, comparable to that of practicing clinicians. Furthermore, there were statistically significant increases in junior clinicians' specificity, PPV, NPV and F1-score in differentiating benign from malignant PGTs when unassisted and model-assisted performance of junior clinicians were compared.

CONCLUSION

Our results provide evidence that deep learning-based method may offer assistance for PGT's binary distinction.

[The influencing factors of functional somatic discomfort in clinical nurses]

Objective: To investigate the functional somatic discomfort status, and to analyze the effect of job stress, hostile attribution bias and ego depletion on functional somatic discomfort in clinical nurses. Methods: In May 2019, 10 cities in Henan Province and Fujian Province were randomly selected as sampling cities. Using the stratified cluster sampling method, nurses of clinical nursing posts in 22 third class hospitals and 23 second class hospitals were selected as the research objects. The general information, job stress, hostile attribution bias, ego depletion and functional somatic discomfort of clinical nurses were investigated by self-designed general information questionnaire, Perceived Stress Scale, Social Information Processing-attribution Bias Questionnaire, Self-regulatory Fatigue Scale, Patient Health Questionnaire-15. 1200 clinical nurses included, and a total of 1159 valid questionnaires were collected, the effective rate of questionnaire collection was 96.6%. The t test was used to compare the difference of the functional somatic discomfort scores of clinical nurses with different demographic characteristicst. The influence of job stress, hostile attribution bias and ego depletion on functional somatic discomfort of clinical nurses were analyzed with Bootstrap. Results: The functional somatic discomfort score of clinical nurses was (8.95±4.38), of which 859 (74.12%) had functional somatic discomfort symptom. The functional somatic discomfort score of clinical nurses aged 36-50 years old was higher than that of 19-35 years old, the functional somatic discomfort score of clinical nurses with service age ≥5 years was higher than that of <5 years, the functional somatic discomfort score of non-permanent clinical nurses was higher than that of permanent clinical nurses, the functional somatic discomfort score of clinical nurses in tertiary hospitals was higher than that of secondary hospitals, the functional somatic discomfort score of clinical nurses in surgical departments were higher than those in non-surgical departments, and the differences were statistically significant (P<0.05). Job stress affected functional somatic discomfort through the single mediating role of hostile attribution bias, the single mediating role of ego depletion, and the chain mediating role of hostile attribution bias and ego depletion (β=0.17, 95%CI: 0.10-0.20; β=0.16, 95%CI: 0.10-0.20; β=0.07, 95%CI: 0.03-0.10; P<0.05) . Conclusion: The functional somatic discomfort symptoms of clinical nurses are significant and varied among different age, working age, employment form, hospital grade and department groups. They are affected by work stress directly and through the separate mediating effect of hostile attribution bias and ego depletion, and the chain mediating effect of hostile attribution bias and ego depletion.

Diselenide-Based Dual-Responsive Prodrug as Pyroptosis Inducer Potentiates Cancer Immunotherapy

Pyroptosis is demonstrated to trigger antitumor immunity and represents a promising new strategy to potentiate cancer immunotherapy. The number of potent pyroptosis inducers, however, is limited and without tumor-targeting capability, which inevitably causes damage in normal tissues. Herein, a small molecular prodrug of paclitaxel-oxaliplatin is rationally synthesized, which can be covalently self-assembled with diselenide-containing cross-linking (Dse11), producing a diselenide nanoprodrug (DSe@POC) to induce pyroptosis for the first time. The diselenide bonds within DSe@POC can be split by high glutathione in the tumor microenvironment (TME) and reactive oxygen species induced by photodynamic therapy, thus possessing excellent TME on-target effects. Additionally, DSe@POC is able to elicit intense pyroptosis to remodel the immunostimulated TME and trigger a robust immune response. Furthermore, combined αPD-1 therapy effectively inhibits the growth of remote tumors through the abscopal effect, amplifies a long-term immune memory response to reject rechallenged tumors, and prolongs survival. Collectively, DSe@POC, as the first TME dual-responsive diselenide-based pyroptosis inducer, will open up an attractive approach for cancer immunotherapy.

Predicting the Proliferation of Tongue Cancer With Artificial Intelligence in Contrast-Enhanced CT

Tongue squamous cell carcinoma (TSCC) is the most common oral malignancy. The proliferation status of tumor cells as indicated with the Ki-67 index has great impact on tumor microenvironment, therapeutic strategy making, and patients’ prognosis. However, the most commonly used method to obtain the proliferation status is through biopsy or surgical immunohistochemical staining. Noninvasive method before operation remains a challenge. Hence, in this study, we aimed to validate a novel method to predict the proliferation status of TSCC using contrast-enhanced CT (CECT) based on artificial intelligence (AI). CECT images of the lesion area from 179 TSCC patients were analyzed using a convolutional neural network (CNN). Patients were divided into a high proliferation status group and a low proliferation status group according to the Ki-67 index of patients with the median 20% as cutoff. The model was trained and then the test set was automatically classified. Results of the test set showed an accuracy of 65.38% and an AUC of 0.7172, suggesting that the majority of samples were classified correctly and the model was stable. Our study provided a possibility of predicting the proliferation status of TSCC using AI in CECT noninvasively before operation.

Improved Diagnostic Accuracy of Ameloblastoma and Odontogenic Keratocyst on Cone-Beam CT by Artificial Intelligence

OBJECTIVE

The purpose of this study was to utilize a convolutional neural network (CNN) to make preoperative differential diagnoses between ameloblastoma (AME) and odontogenic keratocyst (OKC) on cone-beam CT (CBCT).

METHODS

The CBCT images of 178 AMEs and 172 OKCs were retrospectively retrieved from the Hospital of Stomatology, Wuhan University. The datasets were randomly split into a training dataset of 272 cases and a testing dataset of 78 cases. Slices comprising lesions were retained and then cropped to suitable patches for training. The Inception v3 deep learning algorithm was utilized, and its diagnostic performance was compared with that of oral and maxillofacial surgeons.

RESULTS

The sensitivity, specificity, accuracy, and F1 score were 87.2%, 82.1%, 84.6%, and 85.0%, respectively. Furthermore, the average scores of the same indexes for 7 senior oral and maxillofacial surgeons were 60.0%, 71.4%, 65.7%, and 63.6%, respectively, and those of 30 junior oral and maxillofacial surgeons were 63.9%, 53.2%, 58.5%, and 60.7%, respectively.

CONCLUSION

The deep learning model was able to differentiate these two lesions with better diagnostic accuracy than clinical surgeons. The results indicate that the CNN may provide assistance for clinical diagnosis, especially for inexperienced surgeons.

[The influence of workplace violence on burnout sense in clinical nurses]

Objective: To explore the influence mechanism of intrusive thoughts and ego depletion between effects of workplace violence on burnout sense in clinical nurses. Methods: In May 2019, 10 cities in Henan Province and Fujian Province were selected as sampling cities by the method of grabbing random balls. Using the stratified cluster sampling method, nurses in clinical nursing posts in 22 third class hospitals and 23 second class hospitals were selected as the research objects for a cross-sectional epidemiological survey, including 1200 nurses. A total of 1159 valid questionnaires were collected, and the effective rate was 96.6%. 1159 clinical nurses were investigated by workplace violence scale, event impact scale, self-regulation fatigue scale and job burnout scale. The items contained in the questionnaire were analyzed by exploratory factor analysis with Harman single factor test, and the demographic characteristics of nurses' workplace violence, invasive thinking, self loss and job burnout were compared and analyzed with s-n-k. Results: Those with less than 3 years of service, those with more than 3 years of aggressive thinking and self loss score, and those with less than 3 years of job burnout score; The score of job burnout of unmarried was lower than that of married; The scores of invasive thinking and self loss of non editors were higher than those of current editors; The scores of workplace violence, aggressive thinking, self loss and job burnout of clinical nurses in tertiary hospitals were higher than those in secondary hospitals; The score of job burnout of undergraduate and above is higher than that of junior college and below; The scores of workplace violence, aggressive thinking and self loss of clinical nurses in surgical departments were higher than those in non-surgical departments; The job burnout score of those aged 36 and above was higher than that of those aged <36, The difference was statistically significant (P< 0.05) . Aggressive thinking and self attrition played a mediating role between workplace violence and job burnout. Workplace violence affected job burnout through the single mediating role of aggressive thinking, the single mediating role of self attrition, and the chain mediating role of aggressive thinking self attrition (β=0.16、0.08、0.03, 95%CI: 0.251~0.190、0.121~0.028、0.050~0.012, P<0.05) . Conclusion: Workplace violence affects burnout sense through the independent mediating role of intrusive thoughts and ego depletion and the chain mediating role of intrusive thoughts and ego depletion in clinical nurses.

Propofol ameliorates acute postoperative fatigue and promotes glucagon-regulated hepatic gluconeogenesis by activating CREB/PGC-1α and accelerating fatty acids beta-oxidation

Postoperative fatigue (POF) is the most common and long-lasting complication after surgery, which brings heavy burden to individuals and society. Recently, hastening postoperative recovery receives increasing attention, but unfortunately, the mechanisms underlying POF remain unclear. Propofol is a wildly used general anesthetic in clinic, and inspired by the rapid antidepressant effects induced by ketamine at non-anesthetic dose, the present study was undertaken to investigate the anti-fatigue effects and underlying mechanisms of propofol at a non-anesthetic dose in 70% hepatectomy induced POF model in rats. We first showed here that single administration of propofol at 0.1 mg/kg ameliorated acute POF in hepatectomy induced POF rats. Based on metabonomics analysis, we hypothesized that propofol exerted anti-fatigue activity in POF rats by facilitating free fatty acid (FFA) oxidation and gluconeogenesis. We further confirmed that propofol restored the deficit in FFA oxidation and gluconeogenesis in POF rats, as evidenced by the elevated FFA utilization, acetyl coenzyme A content, pyruvic acid content, phosphoenolpyruvic acid content, hepatic glucose output and glycogen storage. Moreover, propofol stimulated glucagon secretion and up-regulated expression of cAMP-response element binding protein (CREB), phosphorylated CREB, peroxlsome prolifeator-activated receptor-γ coactivator-1α (PGC-1α), phosphoenolpyruvate carboxykinade1 and carnitine palmitoltransferase 1A. In summary, our study suggests for the first time that propofol ameliorates acute POF by promoting glucagon-regulated gluconeogenesis via CREB/PGC-1α signaling and accelerating FFA beta-oxidation.

[Effect of imatinib on the height of children with chronic myeloid leukemia in the chronic phase]

目的

评估伊马替尼对慢性髓性白血病慢性期（CML-CP）儿童身高的影响。

方法

2018年7月至2019年7月，在全国范围内对诊断时年龄<18周岁、接受伊马替尼治疗至少3个月的CML儿童或其家长发放问卷，调查受访者伊马替尼治疗前后身高的变化。主要评价指标为身高标准差积分值（HtSDS）以及标准差积分的差值（ΔHtSDS），并分析其相关影响因素。

结果

共有238例受访者符合标准并被纳入研究，男性138例（58.0％），初诊时中位年龄11.0（1.4～17.9）岁，青春期前93例（39.0％），至填写答卷时，中位年龄15.0（2.0～34.0）岁，中位伊马替尼服药时间28（3～213）个月。受访者填写答卷时HtSDS（−0.063±1.361）较治疗前HtSDS（0.391±1.244）显著下降（P<0.001），71.0％的患儿出现身高增长减慢。青春期前服药者治疗后HtSDS下降显著（P<0.05），而青春期开始后服药者HtSDS变化不明显（P>0.05）。多因素分析显示，服药初始年龄较小（偏回归系数为0.122，B＝0.572，t＝10.733，P<0.001）和服药时间较长（偏回归系数为−0.006，B＝−0.211，t＝−4.062，P<0.001）是伊马替尼抑制身高增长的独立影响因素。

结论

伊马替尼引起CML-CP儿童身高增长障碍，服药初始年龄越小、服药时间越长，伊马替尼对身高的影响越明显。

Effects of three different first-aid training methods on knowledge retention of caregivers and teachers: a randomized and longitudinal cohort study in China

OBJECTIVES

The purpose of this study was to assess the effects of pediatric first-aid training methods on caregivers' and teachers' knowledge retention.

STUDY DESIGN

This was a randomized longitudinal cohort study.

METHODS

A stratified random sampling method was used to select 1282 caregivers and teachers with the help of local education authorities in 18 districts and 1 county of Shanghai, China. The selected caregivers and teachers were randomly allocated into groups that were exposed to 3 models of training, including an interactive training model (group A), lecture-based training model (group B), and video instruction training model (group C), for pediatric first-aid training for caregivers and teachers (PedFACTs). Before and after the training, a descriptive questionnaire composed of demographic information and 37 simple-choice questions about first aid was administered. During the follow-up, 120 caregivers and teachers from each of the three methods were randomized and retested 9 months after their training and 120 caregivers and teachers were randomly reselected in each of the three methods and retested 4 years after their training.

RESULTS

Immediately after training, there was a significant difference in the postassessment results between groups A and B (P = 0.002) as well as between groups A and C (P < 0.001). The average interactive training model score was the highest, followed by the instruction training model and video instruction training model. There was no significant difference among the three groups in the reassessment scores at 9 months and 4 years after training (P = 0.744, P = 0.595). The difference in passing the assessment among the three groups at 9 months or 4 years after training was not maintained at a significant level.

CONCLUSION

The three training methods did not affect knowledge retention of the caregivers and teachers at nine months or four years after training completion. Video instruction may be an effective, convenient, and feasible method to train caregivers and teachers.

[Impact of allergic airway diseases on risk of attention deficit hyperactivity disorder in school-age children]

Objective: To investigate the impact of allergic airway diseases on the risk of attention deficit hyperactivity disorder (ADHD) in school-age children. Method: Used stratified cluster sampling method, school-age children in first to sixth grade in primary schools in 9 randomly selected cities including Shanghai, Guangzhou, Xi'an, and Wuhan were enrolled in the study. Interview of parents with questionnaires, which included school-age individual and family social environment questionnaire (including history of diagnosed ADHD, allergic rhinitis, and bronchial asthma) and Children's Sleep Habits Questionnaire (CSHQ), were finished and collected during November to December in 2005.Diagnosed allergic rhinitis and asthma by specialist were independent variables and divided into following three categories as no allergic diseases (neither allergic rhinitis nor asthma), single allergic disease (allergic rhinitis or asthma), and combined allergic diseases (allergic rhinitis and asthma). Diagnosed ADHD as dependent variable, binary logistic regress model was used to analyze the risks of ADHD in school-age children. Result: Totally 23 791 questionnaires were handed out, while 22 018 were collected. The children had an average age of (8.8±1.8) years, within which 10 869 were male, and 11 021 were female. The risk ratios of ADHD were 2.197 (95%CI: 1.823-2.648) and 3.150 (95%CI: 2.082-4.760) in children with single allergic disease and combined allergic diseases separately. There was no significant difference after adjusting for the factor of sleep habits, as the risk ratios were 2.055 (95%CI: 1.683-2.508) and 3.140 (95%CI: 2.061-4.784) in children with single and combined allergic airway disease separately. Conclusion: Allergic rhinitis and bronchial asthma increased the risk of ADHD, not depending on sleep habits. Hence, allergic airway diseases could be independent risk factors of ADHD.

Associations between parent-reported sleep duration and adiposity in Chinese early adolescents

BACKGROUND

Short sleep duration has recently been found to be associated with obesity in children, but findings involving adolescents have been less consistent, and some have mentioned gender differences.

OBJECTIVES

To investigate the association between parent-reported sleep duration and adiposity in early adolescence (10-12 years old) and to explore gender differences within this population.

METHODS

Participants were 1309 fifth-grade students (685 boys) from 10 primary schools in Shanghai, China. Body mass index (BMI), waist-height ratio (WHeR) and body fat percentage (BF%) were assessed. Sleep and other potential contributors were recorded by parents or self-reported.

RESULTS

Compared with adolescents in the longest sleep group (greater than or equal to +1 SD, ≥10.05 h), those in the shortest sleep group (less than -1 SD, <8.89 h) had significantly higher BMI, WHeR and BF%. Sleep was found to be closely related to increased adiposity in girls who were in the shortest and shorter sleep group (<mean, <9.45 h). No association was found in boys.

CONCLUSIONS

Short sleep duration was associated with higher adiposity indices in early adolescents from China, especially in girls. Interventions focusing on modifying adolescents' sleep habits may potentially prevent obesity and overweight.

Myasthenic syndrome due to defects in rapsyn: Clinical and molecular findings in 39 patients

BACKGROUND

Pathogenic mutations in rapsyn result in endplate acetylcholine receptor (AChR) deficiency and are a common cause of postsynaptic congenital myasthenic syndromes.

METHODS

Clinical, electrophysiologic, pathologic, and molecular studies were done in 39 patients.

RESULTS

In all but one patient, the disease presented in the first 2 years of life. In 9 patients, the myasthenic symptoms included constant or episodic ophthalmoparesis, and 1 patient had a pure limb-girdle phenotype. More than one-half of the patients experienced intermittent exacerbations. Long-term follow-up was available in 25 patients after start of cholinergic therapy: 21 became stable or were improved and 2 of these became asymptomatic; 3 had a progressive course; and 1 died in infancy. In 7 patients who had endplate studies, the average counts of AChR per endplate and the synaptic response to ACh were less reduced than in patients harboring low AChR expressor mutations. Eight patients were homozygous and 23 heterozygous for the common p.N88K mutation. Six mutations, comprising 3 missense mutations, an in-frame deletion, a splice-site mutation, and a nonsense mutation, are novel. Homozygosity for p.N88K was associated with varying grades of severity. No genotype-phenotype correlations were observed except in 8 Near-Eastern patients homozygous for the promoter mutation (c.-38A>G), who had a mild course.

CONCLUSIONS

All but 1 patient presented early in life and most responded to cholinergic agonists. With early diagnosis and therapy, rapsyn deficiency has a benign course in most patients. There was no consistent phenotype-genotype correlation except for an E-box mutation associated with jaw deformities.

Urinary level of nickel and acute leukaemia in Chinese children

The 8-hydroxy-2′-deoxyguanosine (8-OHdG), an oxidized nucleoside of DNA, not only is a widely used biomarker for the measurement of endogenous oxidative DNA damage but might also be a risk factor for many diseases including cancer. Metal exposure may play an important role in oxidative DNA damage among children. However, few studies on urinary 8-OHdG and metals have been conducted in children with acute leukemia. In the present study, urinary Ni and 8-OHdG were examined in 116 children with acute leukaemia (94 acute lymphoid leukaemia [ALL] and 22 acute myeloid leukaemia [AML]) and 51 healthy child controls. Our result showed that urinary Ni in acute leukaemia patients (ALL: 68.40 ± 133.98, AML: 41.48 ± 76.31 ng/mg creatinine) was significantly higher than that in controls (62.47 ± 124.90 vs 17.63 ± 46.17 ng/mg creatinine, P < 0.05). Similarly, the pretherapy level of urinary 8-OHdG in patients (ALL: 11.83 ± 16.23, AML: 12.36 ± 11.36 ng/mg creatinine) was significantly elevated compared with controls (11.92 ± 15.42 vs 4.03 ± 4.70 ng/mg creatinine, P < 0.05). Moreover, urinary 8-OHdG and urinary Ni showed a weak but significant association with increased risk of childhood leukaemia. The present study suggests that Ni may be an etiologic factor for childhood acute leukaemia by oxidative DNA damage.

Novel congenital myasthenic syndromes associated with defects in quantal release

BACKGROUND

Most congenital myasthenic syndromes are caused by defects in postsynaptic or synaptic basal lamina-associated proteins; congenital myasthenic syndromes (CMSs) associated with presynaptic defects are uncommon. Here, the authors describe clinical, electrophysiologic, and morphologic features of two novel and highly disabling CMSs, one determined by presynaptic and the other determined by combined presynaptic and postsynaptic defects.

METHODS

Microelectrode, single channel patch clamp, immunocytochemical, [(125)I]alpha-bungarotoxin binding, and quantitative electron microscopy studies of endplates were performed. Candidate genes were directly sequenced.

RESULTS

Patient 1, a 7-year-old boy, had severe myasthenic symptoms since infancy. Patient 2, a 48-year-old man, had delayed motor milestones and became progressively weaker after age 2 years. Both used wheelchairs and had a 30-50% EMG decrement on 2-Hz stimulation. Evoked quantal release was reduced to approximately 25% of normal in both. In Patient 2, the synaptic response to acetylcholine was further compromised by degeneration of the junctional folds with concomitant loss of the acetylcholine receptor (AChR). A search for mutations in components of the synaptic vesicle release complex and in other candidate proteins failed to identify the molecular basis of the two syndromes.

CONCLUSIONS

Combined clinical, morphologic, and in vitro electrophysiologic findings define two novel congenital myasthenic syndromes. The molecular basis of these syndromes awaits discovery.

Three novel COLQ mutations and variation of phenotypic expressivity due to G240X

OBJECTIVE

To determine the molecular basis and consequences of endplate (EP) acetylcholinesterase (AChE) deficiency.

BACKGROUND

The EP species AChE is an asymmetric enzyme consisting of a tail subunit composed of three collagenic strands (ColQ), each attached to a tetramer of catalytic subunits. The tail subunit is essential for insertion of AChE into the synaptic basal lamina. Human EP AChE deficiency is caused by mutations in COLQ. The authors report three novel COLQ mutations in eight kinships.

METHODS

Immunocytochemistry, electron microscopy, microelectrode recordings, mutation analysis, and expression studies in COS cells were employed.

RESULTS

Two mutations (275insC and Q211X) were heterozygous in one patient. EP studies in this patient revealed no EP AChE, small nerve terminals, reduced presynaptic membrane length, as well as abnormally low-evoked quantal release. The third mutation (G240X) was homozygous in six Palestinian Arab families of the same tribe and in an Iraqi Jewish patient. Expression studies of the three mutations in COS cells indicate that each abrogates formation of insertion competent asymmetric AChE. Although the three mutations have identical predicted consequences at the EP, their phenotypic expressivity varies as regards age at onset, rate of progression, and severity of symptoms.

CONCLUSIONS

1) After mutations in the AChR epsilon subunit, mutations in COLQ are emerging as second most common cause of congenital myasthenic syndromes. 2) A founder effect is likely for G240X in the Palestinian Arab families. 3) That mutations predicting total absence of AChE from the EP have variable phenotypic expressivity suggests that modifying genes or environmental factors can partially compensate for EP AChE deficiency.

Oxidative metabolites of 5-S-cysteinyldopamine inhibit the alpha-ketoglutarate dehydrogenase complex: possible relevance to the pathogenesis of Parkinson's disease

A characteristic change in the substantia nigra of Parkinson's disease patients is an apparent accelerated rate of dopamine oxidation as evidenced by an increased 5-S-cysteinyldopamine (5-S-CyS-DA) to dopamine ratio. However, 5-S-CyS-DA is more easily oxidized than dopamine to give 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxylic acid (DHBT-1). Previous studies have demonstrated that DHBT-1 can be accumulated by intact rat brain mitochondria and inhibits complex I but not complex II respiration. In this study, it is shown that DHBT-1 also inhibits the alpha-ketoglutarate dehydrogenase complex (alpha-KGDH) but not cytochrome c oxidase (complex IV). The inhibition of alpha-KGDH is dependent on the oxidation of DHBT-1, catalyzed by an unknown constituent of the inner mitochondrial membrane, to an electrophilic o-quinone imine that covalently modifies active site sulfhydryl residues. The latter conclusion is based on the ability of > or = equimolar glutathione to block the inhibition of alpha-KGDH by DHBT-1, without altering its rate of mitochondrial membrane-catalyzed oxidation, by scavenging the electrophilic o-quinone intermediate forming glutathionyl conjugates which have been isolated and spectroscopically characterized. Activities of mitochondrial alpha-KGDH and complex I, but not other respiratory complexes, are decreased in the parkinsonian substantia nigra. Such changes together with evidence for accelerated dopamine oxidation, increased formation of 5-S-CyS-DA and the ease of oxidation of this conjugate to DHBT-1 which inhibits alpha-KGDH and complex I, without affecting other respiratory enzyme complexes, suggests that the latter putative metabolite might be an endotoxin that contributes to the alpha-KGDH and complex I defects in Parkinson's disease.

Delta-aminolevulinate dehydratase polymorphism and blood lead levels in Chinese children

This study investigated the relationship between the delta-aminolevulinate dehydratase (ALAD) isozymes and the blood lead levels of Chinese children. The purpose of this study was to determine the precise ALAD genotyping in Chinese children and identify the contribution of the ALAD genotype to the body lead burden. Blood samples were obtained from 109 boys and 120 girls. These children were 6-10 years old and from a single primary school. Both the school and their homes were within a community in which a large smelter was located. An environmental questionnaire was obtained for each subject, and blood lead levels and ALAD isozyme phenotype were analyzed in a double-blinded fashion. The blood lead levels of 229 children ranged from 4.5 to 26.4 microg/dl; the mean was 10.3 microg/dl and the standard deviation was 3.3 microg/dl. The gene distribution of the ALAD isozyme phenotypes in these environmentally exposed children was ALAD 1-1 (92%), ALAD 1-2, (8%), and ALAD 2-2 (0%). The mean blood level of the environmentally exposed children, who were homozygous for the ALAD1 allele, was 9.7 microg/dl; the mean for those who were heterozygous for the ALAD2 allele was 11.7 microg/dl. Using the t test, the means of the groups were different at the level of t=2.2058, P<0.05. Step-wise regression and multiple analyses of covariance were employed to control the confounders to measuring the independent contribution of the ALAD genotype on blood lead levels. After controlling the confounders, the contribution of the ALAD genotype to the blood lead level was greater and still statistically significant (F=7.3201, P<0.01). These results indicate that individuals carrying the ALAD2 allele are more likely to have sustained increases in blood lead levels when exposed to a lead-contaminated environment.

Assessment of bone lead during pregnancy: a pilot study

More than 85% of American children raised in the 1970s had blood lead (BPb) levels >/=10 microg/dL, the level that currently defines childhood Pb poisoning. With exposure and absorption Pb accumulates in bone. Bone Pb release back to blood also occurs, particularly when kinetic rates of bone turnover are elevated. We examined a group of childbearing age, urban African American and Hispanic women to determine whether they had measurable bone Pb and whether bone Pb levels changed during pregnancy. Tibial bone Pb content was assessed sequentially 3 times over 4 months by L-line X-ray fluorescence (LXRF); for pregnant enrollees this occurred during the second and third trimesters and 1-2 months postpartum. LXRF is a noninvasive, low-dose radiation technique that measures superficial cortical bone Pb. Other measures included age, years living in New York City, BPb and a home Pb assessment employing KXRF methodology. Of 53 women evaluated 34 were pregnant. Of these 34, 2 had blood Pb levels >/=10 microg/dL; 2 had bone Pb levels above the minimum detection limit of the instrumentation at the time of enrollment. A case report is presented in which a declining bone Pb level was accompanied by an increase in BPb concentration. We surmise that the prevalence of elevated bone Pb levels will be low in Bronx women despite long-term exposure to leaded paint. However, fetuses of those with elevated bone Pb are at risk of excessive in-utero Pb exposure.

Oxidative metabolites of 5-S-cysteinylnorepinephrine are irreversible inhibitors of mitochondrial complex I and the alpha-ketoglutarate dehydrogenase and pyruvate dehydrogenase complexes: possible implications for neurodegenerative brain disorders

The major initial product of the oxidation of norepinephrine (NE) in the presence of L-cysteine is 5-S-cysteinylnorepinephrine which is then further easily oxidized to the dihydrobenzothiazine (DHBT) 7-(1-hydroxy-2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1, 4-benzothiazine-3-carboxylic acid (DHBT-NE-1). When incubated with intact rat brain mitochondria, DHBT-NE-1 evokes rapid inhibition of complex I respiration without affecting complex II respiration. DHBT-NE-1 also evokes time- and concentration-dependent irreversible inhibition of NADH-coenzyme Q(1) (CoQ(1)) reductase, the pyruvate dehydrogenase complex (PDHC), and alpha-ketoglutarate dehydrogenase (alpha-KGDH) when incubated with frozen and thawed rat brain mitochondria (mitochondrial membranes). The time dependence of the inhibition of NADH-CoQ(1) reductase, PDHC, and alpha-KGDH by DHBT-NE-1 appears to be related to its oxidation, catalyzed by an unknown component of the inner mitochondrial membrane, to electrophilic intermediates which bind covalently to active site cysteinyl residues of these enzyme complexes. The latter conclusion is based on the ability of glutathione to block inhibition of NADH-CoQ(1) reductase, PDHC, and alpha-KGDH by scavenging electrophilic intermediates, generated by the mitochondrial membrane-catalyzed oxidation of DHBT-NE-1, forming glutathionyl conjugates, several of which have been isolated and spectroscopically identified. The possible implications of these results to the degeneration of neuromelanin-pigmented noradrenergic neurons in the locus ceruleus in Parkinson's disease are discussed.

The spectrum of mutations causing end-plate acetylcholinesterase deficiency

The end-plate species of acetylcholinesterase (AChE) is an asymmetric enzyme consisting of a collagenic tail subunit composed of three collagenic strands (ColQ), each attached to a tetramer of the T isoform of the catalytic subunit (AChE(T)) via a proline-rich attachment domain. The principal function of the tail subunit is to anchor asymmetric AChE in the synaptic basal lamina. Human end-plate AChE deficiency was recently shown to be caused by mutations in COLQ. We here report nine novel COLQ mutations in 7 patients with end-plate AChE deficiency. We examine the effects of the mutations on the assembly of asymmetric AChE by coexpressing each genetically engineered COLQ mutant with ACHE(T) in COS cells. We classify the newly recognized and previously reported COLQ mutations into four classes according to their position in ColQ and their effect on AChE expression. We find that missense mutations in the proline-rich attachment domain abrogate attachment of catalytic subunits, that truncation mutations in the ColQ collagen domain prevent the assembly of asymmetric AChE, that hydrophobic missense residues in the C-terminal domain prevent triple helical assembly of the ColQ collagen domain, and that other mutations in the C-terminal region produce asymmetric species of AChE that are likely insertion incompetent.

The spectrum of mutations causing end-plate acetylcholinesterase deficiency

The end-plate species of acetylcholinesterase (AChE) is an asymmetric enzyme consisting of a collagenic tail subunit composed of three collagenic strands (ColQ), each attached to a tetramer of the T isoform of the catalytic subunit (AChE(T)) via a proline-rich attachment domain. The principal function of the tail subunit is to anchor asymmetric AChE in the synaptic basal lamina. Human end-plate AChE deficiency was recently shown to be caused by mutations in COLQ. We here report nine novel COLQ mutations in 7 patients with end-plate AChE deficiency. We examine the effects of the mutations on the assembly of asymmetric AChE by coexpressing each genetically engineered COLQ mutant with ACHE(T) in COS cells. We classify the newly recognized and previously reported COLQ mutations into four classes according to their position in ColQ and their effect on AChE expression. We find that missense mutations in the proline-rich attachment domain abrogate attachment of catalytic subunits, that truncation mutations in the ColQ collagen domain prevent the assembly of asymmetric AChE, that hydrophobic missense residues in the C-terminal domain prevent triple helical assembly of the ColQ collagen domain, and that other mutations in the C-terminal region produce asymmetric species of AChE that are likely insertion incompetent.

Myopathy, myasthenic syndrome, and epidermolysis bullosa simplex due to plectin deficiency

Plectin, an intermediate filament linking protein, is normally associated with the sarcolemma, nuclear membrane, and intermyofibrillar network in muscle, and with hemisdesmosomes in skin. A 20-year-old female with epidermolysis bullosa simplex since birth had progressive ocular, facial, limb, and trunkal weakness and fatigability since age 9, fivefold CK elevation, a 25% decrement with myopathic motor unit potentials and increased electrical irritability on electromyography, and no anti-acetylcholine receptor (AChR) antibodies. Plectin expression was absent in muscle and severe plectin deficiency was noted in skin. Morphologic studies revealed necrotic and regenerating fibers and a wide spectrum of ultrastructural abnormalities: large accumulations of heterochromatic and lobulated nuclei, rare apoptotic nuclei, numerous cytoplasmic and few intranuclear nemaline rods, disarrayed myofibrils, thick-filament loss, vacuolar change, and pathologic alterations in membranous organelles. Many endplates (EPs) had an abnormal configuration with chains of small regions over the fiber surface and a few displayed focal degeneration of the junctional folds. The EP AChR content was normal. In vitro electrophysiologic studies showed normal quantal release by nerve impulse, small miniature EP potentials, and fetal as well as adult AChR channels at the EP. Our findings support the notion that plectin is essential for the structural integrity of muscle and skin, and for normal neuromuscular transmission.

Acetylcholine receptor M3 domain: stereochemical and volume contributions to channel gating

By defining the functional defect in a congenital myasthenic syndrome (CMS), we show that the third transmembrane domain (M3) of the muscle acetylcholine receptor governs the speed and efficiency of gating of its channel. The clinical phenotype of this CMS results from the mutation V285I in M3 of the alpha subunit, which attenuates endplate currents, accelerates their decay and causes abnormally brief acetylcholine-induced single-channel currents. Kinetic analysis of engineered alpha V285I receptors demonstrated a predominant effect on channel gating, with abnormally slow opening and rapid closing rates. Analysis of site-directed mutations revealed stereochemical and volume-dependent contributions of alpha V285 to channel gating. Thus, we demonstrate a functional role for the M3 domain as a key component of the nicotinic acetylcholine receptor channel-gating mechanism.

Brain mitochondria catalyze the oxidation of 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxyli c acid (DHBT-1) to intermediates that irreversibly inhibit complex I and scavenge glutathione: potential relevance to the pathogenesis of Parkinson's disease

We have proposed that a very early step in the pathogenesis of idiopathic Parkinson's disease is the elevated translocation of L-cysteine into neuromelanin-pigmented dopaminergic neurons in the substantia nigra. This influx of L-cysteine was proposed to divert the normal neuromelanin pathway by scavenging dopamine-o-quinone, formed by autoxidation of cytoplasmic dopamine, to give initially 5-S-cysteinyldopamine, which is further oxidized to 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxylic acid (DHBT-1). In a recent report, it was demonstrated that DHBT-1 evokes inhibition of complex I respiration when incubated with intact rat brain mitochondria and a time-dependent irreversible inhibition of NADH-coenzyme Q1 (CoQ1) reductase when incubated with mitochondrial membranes. In this study, it is established that the time dependence of NADH-CoQ1 reductase inhibition reflects the oxidation of DHBT-1, catalyzed by an unknown constituent of the inner mitochondrial membrane, to an o-quinone imine intermediate that rearranges to 7-(2-aminoethyl)-5-hydroxy-1,4-benzothiazine-3-carboxylic acid (BT-1) and decarboxylates to 7-(2-aminoethyl)-5-hydroxy-1,4-benzothiazine (BT-2), which are further catalytically oxidized to o-quinone imine intermediates. The electrophilic o-quinone imine intermediates formed in these mitochondria-catalyzed oxidations of DHBT-1, BT-1, and BT-2 are proposed to bind covalently to key sulfhydryl residues at the complex I site, thus evoking irreversible inhibition of NADH-CoQ1 reductase. Evidence for this mechanism derives from the fact that greater than equimolar concentrations of glutathione completely block inhibition of NADH-CoQ1 reductase by DHBT-1, BT-1, and BT-2 by scavenging their electrophilic o-quinone imine metabolites to form glutathionyl conjugates. The results of this investigation may provide insights into the irreversible loss of glutathione and decreased mitochondrial complex I activity, which are both anatomically specific to the substantia nigra and exclusive to Parkinson's disease.

Low-level prenatal lead exposure and neurobehavioral development of children in the first year of life: a prospective study in Shanghai

We used a prospective study design to assess the effects of prenatal low-level lead exposure on the development of urban, inner-city children in Shanghai. Umbilical cord blood samples wee consecutively collected from 605 live newborns. Two hundred and fifty-seven samples were excluded from the study due to clotting. Lead levels were determined on 348 cord blood samples. The geometric mean was 9.2 micrograms/dl. Based on their cord blood lead levels, infants were classified into two exposure groups: 104 in a relatively low lead group (lead levels < or = 30 percentile), and 104 in a relatively high lead group (lead levels > or = 70 percentile). Seventy-five subjects failed to complete the study, and 133 babies were included in the final cohort: 69 babies in the high lead group and 64 in the low lead group. At 3, 6, and 12 months, the Bayley Scales of Infant Development were administered and capillary blood lead levels were measured. Detailed information was obtained on a wide range of variables relevant to infant development. At all three ages, the Mental Development index (MDI) scores, adjusted for confounders, were inversely related to the infants' cord blood lead levels. The difference of the mean adjusted MDI scores between low and high lead groups was 3.4 at 3 months, 6.3 at 6 months, and 5.2 at 12 months of age. These differences were statistically significant at all time points. No significant association between cord blood lead levels and the Psychomotor Development Index (PDI) scores was detected at all three visits after adjustment for confounders. Postnatal lead levels were unrelated to concurrent developmental status. We conclude that prenatal low-level lead exposure, which is relatively common in Shanghai, is associated with an adverse developmental impact on children through the first year of life.

Electrophysiological and biochemical responses of mouse vomeronasal receptor cells to urine-derived compounds: possible mechanism of action

Receptor cells of the vomeronasal organ (VNO) are thought to detect pheromone-like molecules important for reproductive physiology. Several compounds derived from male mouse urine have been demonstrated to affect endocrine events in female mice. In the present study, the ability of these compounds to affect VNO activity was tested. In dissociated VNO cells held under voltage clamp conditions, application of dehydro-exo-brevicomin (DHB) evoked an outward current at negative holding potentials and an inward current at positive holding potentials. Under current clamp, DHB reduced action potential firing. Since DHB application caused a decrease in membrane conductance, this compound appeared to act by reducing inward current through closing an ion channel. Biochemical experiments tested the effects of DHB and 2-(sec-butyl)-4,5-dihydrothiazole (SBT) on cAMP levels in the VNO. A mixture of DHB and SBT decreased cAMP levels in VNO sensory tissue and had no effect on VNO non-sensory tissue. The results suggest that pheromones have an inhibitory influence on action potential generation and on cAMP levels in receptor cells of the VNO.

Iron- and manganese-catalyzed autoxidation of dopamine in the presence of L-cysteine: possible insights into iron- and manganese-mediated dopaminergic neurotoxicity

Iron(II/III) and manganese(II) both catalyze the autoxidation of the neurotransmitter dopamine (DA) in the presence of L-cysteine (CySH) in buffered aqueous solution at pH 7.4. Fe2+/Fe3+ and CySH together generate the hydroxyl (HO.) and cysteinyl thiyl (CyS.) radicals. DA is oxidized by HO. to DA semiquinone radical species that either react with CyS. to give 5-S-cysteinyldopamine (5-S-CyS-DA), 2-S-CyS-DA, and 6-S-CyS-DA or disproportionate to DA-o-quinone that reacts with CySH to give the same cysteinyl conjugates of DA. The major product of this initial reaction is 5-S-CyS-DA. However, 5-S-CyS-DA can be further oxidized by HO. to an o-quinone (2) that undergoes intramolecular cyclization to an o-quinone imine (3). The latter intermediate is the precursor of the dihydrobenzothiazine (DHBT) 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1, 4-benzothiazine-3-carboxylic acid (DHBT-1) and several other cyclized products. However, cysteinyl conjugates of DA can also be oxidized by HO. in a one-electron abstraction reaction that leads to DA thiyl radicals. Reactions of these radicals with CyS. or DA semiquinone radicals lead to some novel DA disulfides and thioethers, respectively. The Mn(II)-catalyzed oxidation of DA generates DA-o-quinone that is scavenged by CySH to give 5-S-CyS-DA (major initial product) with lower yields of other cysteinyldopamines. Subsequent Mn(II)-catalyzed oxidation of 5-S-CyS-DA gives o-quinone 2 and thence o-quinone imine 3 that serve as the precursors of DHBT-1 and several other DHBTs. Organic or oxygen radicals do not play significant roles in the Mn(II)-catalyzed oxidation of DA in the presence of CySH. Recent studies have demonstrated that DHBT-1 can be accumulated by brain mitochondria and evoke irreversible inhibition of NADH-coenzyme Q reductase (complex I). Furthermore, iron, manganese, and alterations in glutathione and CySH metabolism have been implicated in the selective degeneration of nigrostriatal dopaminergic neurons in idiopathic and chemically induced Parkinson's disease (PD). Because DHBT-1 is formed in both the iron- and manganese-catalyzed oxidation of DA in the presence of CySH and a defect in mitochondrial complex I respiration contributes to dopaminergic neuronal cell death in PD, the results of this investigation are discussed in terms of their possible implications to an understanding of the neuropathological processes in idiopathic and chemically induced parkinsonism.

Mode switching kinetics produced by a naturally occurring mutation in the cytoplasmic loop of the human acetylcholine receptor epsilon subunit

We describe the genetic and kinetic defects in a congenital myasthenic syndrome caused by heteroallelic mutations of the acetylcholine receptor (AChR) epsilon subunit gene. The mutations are an in-frame duplication of six residues in the long cytoplasmic loop (epsilon1254ins18) and a cysteine-loop null mutation (epsilonC128S). The epsilon1254 ins18 mutation causes mode switching in the kinetics of receptor activation in which three modes activate slowly and inactivate rapidly. The epsilon1245ins18-AChR at the endplate shows abnormally brief activation episodes during steady state agonist application and appears electrically silent during the synaptic response to acetylcholine. The phenotypic consequences are endplate AChR deficiency, simplification of the postsynaptic region, and compensatory expression of fetal AChR that restores electrical activity at the endplate and rescues the phenotype.

Urine-derived compound evokes membrane responses in mouse vomeronasal receptor neurons

Sensory neurons of the vomeronasal organ (VNO) are thought to detect species-specific chemical signals important for reproductive function. The electrical properties of VNO neurons have begun to be characterized in a variety of species; however, the response of VNO neurons to possible physiological ligands has not yet been reported. One physiological effector, dehydro-exo-brevicomin (DHB), is found in the urine of intact male mice and affects the estrous cycle of female mice. In the present study, dissociated VNO neurons were voltage- or current-clamped and their response to DHB was determined. Approximately 26% of VNO neurons responded to DHB with an outward current at negative holding potentials; the current reversed at approximately +4 mV. Application of DHB in current-clamp mode produced membrane hyperpolarization and/or a reduction in the firing of action potentials. Because membrane conductance was shown to be decreased during application of DHB, the results suggest that the outward current associated with DHB application is a reflection of a reduction in inward current caused by closing an ion channel. This study provides the first evidence that a compound found in male urine directly affects VNO neurons.

Umbilical cord blood lead levels in Shanghai, China

This study was designed to determine the cord blood lead (BPb) levels of babies born in one urban area of Shanghai, and to preliminarily identify the demographic, social environment and prenatal factors which have an effect on the cord BPb concentrations. From August to November 1993, umbilical cord blood samples were obtained from 605 live newborns in the Yangpu Maternal and Child Hospital. 257 samples were excluded from measurement because of clotting. In 348 cord samples, the geometric mean of cord BPb levels was 9.2 micrograms/dl, with a 95% confidence interval of the mean 8.86-9.54 (micrograms/dl). 142 babies (40.8%) had cord BPb levels of 10 micrograms/dl or greater. As a result of this high percentage of newborns with BPb levels equal to or greater than 10 micrograms/dl, we estimate that each year in the Shanghai City about 60,000 newborns are at risk for developing neuropsychological deficiencies caused by maternal lead exposure during pregnancy. To investigate the factors affecting cord blood levels, the subjects with levels greater than the 70th percentile (10.7 micrograms/dl) (n = 104) and less than the 30th percentile (7.4 micrograms/dl) (n = 104) were selected to compare the demographic, environment and prenatal medical history. Increased BPb levels at birth were associated with maternal passive smoking, a family member being occupationally exposed to lead, proximity to major traffic way, household coal combustion, neighborhood coal combustion, low level of maternal occupations, and the increasing occurrence of having the high lead foodstuff pidan (preserved duck egg) during pregnancy. We conclude that prenatal lead exposure has become an important health issue for young children in Shanghai.

Oxidation of dopamine in the presence of cysteine: characterization of new toxic products

Previous studies demonstrated that oxidation of dopamine (DA) in the presence of L-cysteine (CySH) at pH 7.4 gives a complex mixture of cysteinyl conjugates of the neurotransmitter that can be easily further oxidized to a number of dihydrobenzothiazines (DHBTs) along with unidentified yellow products. In this investigation, three of these products have been identified. 7-(2 Aimoethyl)-5-hydroxy-1,4-benzothiazine-3-carboxylic acid (BT-1) is formed as a result of oxidation of 5-S-cysteinyldopamine (5-S-CyS-DA) and 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxylic acid (DHBT-1). Regioisomers 6-(2-aminoethyl)-1,8,9,10-tetrahydrobenzo[1,2-b:4,3-b']bis[1,4] thiazine-9-carboxylic acid (12) and 6-(2-aminoethyl)-1,2,3,10-tetrahydrobenzo[1,2-b:4,3-b']bis[1,4] thiazine-2-carboxylic acid (13) are formed by oxidation of 2,5-bi-S-CyS-DA), 6-S-cysteinyl-7-(2-aminoethyl)-3-4-dihydro-5-hydroxy-2H-1, 4-benzothiazine-3-carboxylic acid (DHBT-2) and 6-S-cysteinyl-8(2-aminoethyl)-3,4-dihydro-2H-1,4-benzothiazine-3-carboxy lic acid (DHBT-6). 2,5-Bi-S-CyS-DA, DHBT-2, and DHBT-6 are major early products of DA oxidation in the presence of CySH. However, because these three compounds are the most easily oxidized products formed in this reaction, they are subsequently transformed into 12 and 13, the latter regioisomer always being the major product. Both 12 (LD50 = 18.5 micrograms) and 13 (LD50 = 1.5 microgram) are lethal when administered into the brains of mice and evoke hyperactivity and tremor. The potential relevance of the in vitro chemistry described in this and earlier reports to reaction that might occur in neuromelanin-pigmented dopaminergic neurons in Parkinson's disease is discussed.

Synthesis, redox properties, in vivo formation, and neurobehavioral effects of N-acetylcysteinyl conjugates of dopamine: possible metabolites of relevance to Parkinson's disease

A very early event in the pathogenesis of idiopathic Parkinson's disease (PD) has been proposed to be an elevated translocation of L-cysteine (CySH) and/or glutathione (GSH) into pigmented dopaminergic cell bodies in the substantia nigra (SN) in which cytoplasmic dopamine (DA) is normally autoxidized to DA-o-quinone as the first step in a reaction leading to black neuromelanin polymer. Such an elevated influx of CySH and GSH would be expected to initially result in formation of 5-S-cysteinyldopamine (5-S-CyS-DA) and 5-S-glutathionyldopamine (5-S-Glu-DA), respectively, and might account for the massive irreversible loss of GSH and progressive depigmentation of SN cells that occurs in the Parkinsonian brain. However, 5-S-Glu-DA has not been detected in the Parkinsonian brain. Furthermore, although the 5-S-CyS-DA/DA and 5-S-CyS-DA/homovanillic acid concentration ratios increase significantly in the SN and cerebrospinal fluid, respectively, of PD patients, the absolute concentrations of 5-S-CyS-DA are extremely low and similar to those measured in age-matched control patients. One explanation for these observations is that 5-S-CyS-DA might be intraneuronally oxidized to more complex cysteinyldopamines and a number of dihydrobenzothiazines (DHBTs) and benzothiazines (BTs). Similarly, 5-S-Glu-DA might be intraneuronally oxidized to more complex glutathionyldopamines. In this investigation, however, it is demonstrated that 5-S-Glu-DA is rapidly metabolized in rat brain to 5-S-CyS-DA and 5-S-(N-acetylcysteinyl) dopamine (5) in reactions mediated by gamma-glutamyl transpeptidase (gamma-GT) and cysteine conjugate N-acetyltransferase. Similarly, 5-S-CyS-DA is metabolized to 5 in rat brain although more slowly than 5-S-Glu-DA. These reactions occur most rapidly in the midbrain, a region that contains the SN. Furthermore, 5, 2-S-(N-acetylcysteinyl)dopamine (6) and 2,5-di-S-(N-acetylcysteinyl)-dopamine (9) are toxic when administered into mouse brain having LD50 values of 14, 25, and 42 micrograms, respectively, and evoke a profound hyperactivity syndrome. These results suggest that the failure to detect 5-S-Glu-DA and the presence of only very low levels of 5-S-CyS-DA in Parkinsonian SN tissue and CSF might be related to both their intraneuronal oxidation and extraneuronal metabolism to N-acetylcysteinyl conjugates of DA. Furthermore, the toxic properties and neurobehavioral responses evoked by 5, 6, and 9 raise the possibility that these N-acetylcysteinyl conjugates of DA, in addition to certain cysteinyldopamines, DHBTs and BTs, might include endotoxins that contribute to SN cell death and other neuronal damage that occurs in PD. Methods are described for the synthesis of several N-acetylcysteinyl conjugates of DA, and their redox behaviors have been studied using cyclic voltammetry.

Further insights into the influence of L-cysteine on the oxidation chemistry of dopamine: reaction pathways of potential relevance to Parkinson's disease

The initial step in the genesis of neuromelanin, a black polymeric pigment normally found in the cytoplasm of dopaminergic cell bodies in the substantia nigra (SN), is the autoxidation of dopamine (DA) to DA-o-quinone (1). In this investigation, it is demonstrated that in the presence of L-cysteine (CySH) o-quinone 1 is scavenged to give 5-S-cysteinyldopamine (5-S-Cys-DA, major product) and 2-S-cysteinyldopamine (2-S-CyS-DA, minor product). These cysteinyl conjugates are more easily oxidized than DA. The relative yields of the resulting products are dependent on the concentration of free CySH. These products include 2,5-bi-S-cysteinyldopamine (2,5-bi-S-CyS-DA) and 2,5,6-tri-S-cysteinyldopamine (2,5,6-tri-S-CyS-DA), 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxylic acid (DHBT-1), 8-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxylic acid (DHBT-5), and a number of cysteinyl conjugates of these dihydrobenzothiazines (DHBTs). 2,5-Bi-S-CyS-DA, DHBT-1, the 6-S-cysteinyl conjugate of DHBT-1, DHBT-5, and the 6-S-cysteinyl conjugate of DHBT-5 were lethal when administered into the brains of laboratory mice and evoke a very characteristic hyperactivity syndrome and episodes of severe tremor. These and related results provide support for the hypothesis that the massive, irreversible loss of glutathione (GSH), increased 5-S-CyS-DA/DA concentration ratio, and depigmentation of dopaminergic neurons in the SN that all occur in Parkinson's disease (PD) might be caused by the gamma-glutamyl transpeptidase-mediated translocation of CySH (and/or GSH) into these cells. Furthermore, the resulting cysteinyldopamines and DHBTs might include endotoxic metabolites responsible for the selective degeneration of nigrostriatal dopaminergic neurons and PD.

Oxidation chemistry of (-)-norepinephrine in the presence of L-cysteine

The noradrenergic neurotransmitter (-)-norepinephrine (1) is very easily oxidized at physiological pH to an o-quinone (2) that normally cyclizes and subsequently oxidatively polymerizes to black melanin. In this investigation it is demonstrated that L-cysteine (CySH) can divert the melanin pathway by efficiently scavenging o-quinone 2 to give, initially, 5-S-cysteinylnorepinephrine (6) and 2-S-cysteinylnorepinephrine (7). These cysteinyl conjugates are appreciably more easily oxidized than 1 to o-quinones that, in part, are further attacked by CySH to give 2,5-bi-S-cysteinylnorepinephrine (8), an even more easily oxidized compound. The o-quinone intermediates formed upon oxidation of 6-8 can also undergo facile intramolecular cyclizations to bicyclic o-quinone imines that oxidize the cysteinyl conjugates from which they are derived in a reaction sequence that leads initially to a number of dihydrobenzothiazines. At least two of these compounds, 7-(1-hydroxy-2-aminoethyl)-3,4-dihydro-5- hydroxy-2H-1,4-benzothiazine-3-carboxylic acid (9) and 8-(1-hydroxy-2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1, 4-benzothiazine-3-carboxylic acid (10) are lethal when administered into the brains of mice. The in vitro chemical pathways elucidated in this investigation might be of relevance to the depigmentation and degeneration of neuromelanin-pigmented noradrenergic cell bodies in the locus ceruleus in Parkinson's Disease and to the degeneration of noradrenergic nerve terminals in Alzheimer's Disease and following transient cerebral ischemia (stroke).

Effect of positioning on pulmonary function of newborns: comparison of supine and prone position

The effect of positioning on pulmonary function has been previously evaluated, and the prone position has been reported to be preferable for neonates with various respiratory diseases. Studies in healthy neonates have yielded conflicting results. Using a crying pulmonary function test, we examined the effect of positioning on pulmonary function in healthy full-term neonates. Thirty-nine infants with a mean birthweight (+/- SD) of 3,140 +/- 379 g and a mean gestational age (+/- SD) of 39.8 +/- 1.6 weeks were investigated during the first 6 hours of life. Measurements were obtained in both supine and prone positions using a computerized volume-flow system. There were statistically significant decreases in crying vital capacity (CVC) and peak expiratory flow rate (PEF) in the prone compared with the supine position. However, there were no significant differences in forced expiratory flow rate at 75% (V(75)), 50% (V(55)), and 25% (V(25)) of vital capacity between the two positions. These results suggest that prone positioning decreases lung volume and increases resistance of upper airways. We conclude that healthy neonates should be in the supine posture for optimal ventilation.

[Study on the efficacy of genetically engineered vaccines against hepatitis B for interruption of perinatal transmission]

The infectivity rate of newborn babies who had been borne from HBsAG(+), HBeAg(+) and anti-HBc(+) mothers was very high (85%). 142 babies born in the hospital were divided into three groups, in this study. In the group 1, 57 babies were inoculated with 20 micrograms recombinant DNA vaccinia vaccines against hepatitis B. The injections were given at newborn, 1 month, and 6 months, respectively. In group 2, 41 babies were inoculated with 20 micrograms genetic engineering vaccines against hepatitis B at same time were intervals as group 1. In group 3, 44 newborn babies were inoculated with 10 micrograms as same vaccines as group 2 HBIG plus 1ml (200 U/ml), at same time intervals as group 1. The immune pretection rates of newborn babies in three groups were 88.2%, 85.9% and 100%, respectively. The anti-HBs pasitive conversion rates were 82%, 86% and 98%, respectively. The group 3 was compared with group 1 and 2. Statistical analysis showed the significant differences (P < 0.05). The result showed the immune program of group 3 was superior to that of group 1 and 2, and none of the 44 babies in group 3 were infected. The efficacy of immunization by genetic engineering vaccines were superior to that of blood-derived vaccine. The genetic engineering vaccines against hepatitis B would be more useful for interruption of perinatal transmission of HBV.

Effects of alloxan on electric activity of mouse pancreatic B cells in vitro

Microelectrode method for recording membrane potentials was used. It was observed that alloxan possessed stimulative and toxic dual effects on the electric activity of pancreatic B cells. A 10-min exposure to alloxan 14 mmol.L-1 in the perfusion medium without glucose caused a significant depolarization of B cells from -44 +/- 13 mV to -36 +/- 12 mV (n = 7, P < 0.05) and evoked spikes in B cells. But the spikes disappeared at 24 +/- 12 min (n = 8). In the presence of glucose 5.5 mmol.L-1 or 11.0 mmol.L-1, the dual effects became weaker or not obvious. After 10-min exposure to diazoxide (an ATP sensitive K+ channel opener) 0.8 mmol.L-1 in the perfusion medium with alloxan 14 mmol.L-1 but devoid of glucose, the amplitude of membrane potential went up from -31 +/- 11 mV to -48 +/- 21 mV and the mean value of spikes dropped from 31 +/- 24 spikes.min-1 to 5 +/- 5 spikes.min-1. It was suggested that the stimulative effect of alloxan was due to blocking of ATP sensitive K+ channel and a higher concentration of glucose could prevent B cells from alloxan injury.

The adverse effect of marginally higher lead level on intelligence development of children: a Shanghai study

We surveyed 128 preschool children in a lead-polluted area in Shanghai to study the relationship between blood lead level and neuropsychological functions, assessed by age-appropriate psychological tests. The geometric means of blood lead level was 21.7 + -10.8 micrograms/dl. Of 47 children aged below 30 months, there was no significant difference in BSID indices between the high and low lead subjects, although the high lead children tended to have poorer development scores than the low lead ones. On the other hand, of 81 children older than 46 months, the WPPSI IQ scores showed highly significant negative correlation with blood lead level. Step-wise regression and multiple analysis of covariance techniques were employed to find out and control the confounding factors. Even when 21 non-lead variables were considered, the IQ difference between high and low lead groups remained statistically significant. We concluded that the children, especially those older than 46 months, in the area investigated, did suffer from lead toxicity causing impairment in intelligence development. We support the view that marginally higher lead level in children should be taken seriously.

Effects of substance P on electric activity of mouse pancreatic islet cells in vitro

The effects of substance P (SP), [D-Pro2, D-Trp7,9]SP and verapamil on the electric activity of B cells of Langerhans islets of mice were investigated. Addition of SP 100 nmol.L-1 to the perfusion medium stimulated spontaneous electric activity induced by glucose 5.5 mmol.L-1 with an increase in frequency and amplitude of the spikes. [D-Pro2, D-Trp7,9]SP 50 nmol.L-1 reversed the stimulative effect of SP. There was no evidence for an enhancing interaction between SP and acetylcholine 1 mumol.L-1. Verapamil 60 mumol.L-1 blocked the stimulative effect of SP. These results suggest that the stimulative effect of SP on the electric activity of B cells may be due to the increase in Ca2+ influx through the voltage-dependent Ca2+ channels.