A descriptive evaluation of resident prescription writing errors and self-perceived learning needs in dermatology.

Prescribing errors in medical practice are common, and may be preventable in a significant proportion of cases. The literature on dermatological prescription errors is scarce. We sought to determine the rate and causes of resident prescribing errors in an outpatient dermatology practice, and surveyed residents' self-perceived prescription writing learning needs. All prescription errors were tabulated at the Ricky Kanee Schachter Dermatology Clinic (Women's College Hospital) from November 2019 to January 2020. There was an overall prescribing error rate of 1.58% (23/1457), with no significant difference between topical and systemic drugs (1.85% and 0.86%, respectively; P = 0.20) or between written prescriptions and those created by the electronic medical record (1.66% and 1.29%, respectively; P = 0.84). The survey response rate was 26.2% (22/82), with respondents reporting their overall confidence in dermatology prescription writing as (mean ± SD) 7.14 ± 1.75 out of 10. While the resident prescribing error rate was relatively low, multiple errors were avoidable, and residents agree that targeted dermatology-specific training in prescription writing is needed.

Detection of Ancestry Information of Urumqi Mongolians Based on the AIM-InDels Loci Multiplex System.

ABSTRACT: Objective To explore the genetic background and structure of Urumqi Mongolians, the previously developed 39-AIM-InDels panel for ancestry inference was utilized in the present study. Methods The blood samples of 145 unrelated healthy Urumqi Mongolian individuals were collected and genotyped. The compositions of ancestry information of Urumqi Mongolians were studied with 17 different populations from three continents （East Asia, Europe and Africa） as reference populations. Then, multiple population genetics and bioinformatics analysis methods were applied, the Fst and DA values between matched populations were compared and analyzed, PCA analysis was performed and a phylogenetic tree was constructed. The proportions of ancestry information components of Urumqi Mongolians were analyzed with Structure software, etc. Results The ancestry information components of Urumqi Mongolian group in different intercontinental populations accounted for 89%, 7%, and 3% of East Asian, European, and African populations, respectively. Compared with other intercontinental populations, Urumqi Mongolian group and East Asian populations have lower Fst and DA values, and they were in the same cluster in PCA analysis as well. In a phylogenetic tree, the Urumqi Mongolian group was in the same branch as East Asian populations. Conclusion Urumqi Mongolian group had relatively close genetic relationships with East Asian populations, and the proportion of its East Asian ancestry was about 89%.

Surface-enhanced Raman spectroscopic analysis of N6-benzylaminopurine residue quantity in sprouts with gold nanoparticles.

A rapid and quantitative method for the determination of N6-Benzylademine (N6-BA) was established through the application of surface-enhanced Raman spectroscopy (SERS). The Raman peak intensities of N6-BA at 1002 cm-1 positively correlated to N6-BA concentrations in sprout extracts. The R2 reached 0.99, and RSDs calculated below 10% at the concentration range of 0.1 ∼5µg mL-1. The average recoveries were 80.0% ∼ 98.2% for blank samples intentionally contaminated at differing levels of 0.04, 0.4, and 1 µg g-1. The whole procedure, including sample preparation and SERS detection, did not exceed 30 min for a set of 6 samples. This study indicates that SERS is a promising technique for rapid tracing analysis and on-site testing of N6-BA.

G protein-coupled estrogen receptor inhibits the P2Y receptor-mediated Ca(2+) signaling pathway in human airway epithelia.

P2Y receptor activation causes the release of inflammatory cytokines in the bronchial epithelium, whereas G protein-coupled estrogen receptor (GPER), a novel estrogen (E2) receptor, may play an anti-inflammatory role in this process. We investigated the cellular mechanisms underlying the inhibitory effect of GPER activation on the P2Y receptor-mediated Ca(2+) signaling pathway and cytokine production in airway epithelia. Expression of GPER in primary human bronchial epithelial (HBE) or 16HBE14o- cells was confirmed on both the mRNA and protein levels. Stimulation of HBE or 16HBE14o- cells with E2 or G1, a specific agonist of GPER, attenuated the nucleotide-evoked increases in [Ca(2+)]i, whereas this effect was reversed by G15, a GPER-specific antagonist. G1 inhibited the secretion of two proinflammatory cytokines, interleukin (IL)-6 and IL-8, in cells stimulated by adenosine 5'-(γ-thio)triphosphate (ATPγS). G1 stimulated a real-time increase in cAMP levels in 16HBE14o- cells, which could be inhibited by adenylyl cyclase inhibitors. The inhibitory effects of E2 or G1 on P2Y receptor-induced increases in Ca(2+) were reversed by treating the cells with a protein kinase A (PKA) inhibitor. These results demonstrated that the inhibitory effects of G1 or E2 on P2Y receptor-mediated Ca(2+) mobilization and cytokine secretion were due to GPER-mediated activation of a cAMP-dependent PKA pathway. This study has reported, for the first time, the expression and function of GPER as an anti-inflammatory component in human bronchial epithelia, which may mediate through its opposing effects on the pro-inflammatory pathway activated by the P2Y receptors in inflamed airway epithelia.

Practical approach to non-alcoholic fatty liver disease in patients with diabetes.

The prevalence of Type 2 diabetes is expected to increase in parallel with obesity rates and the ageing population. Recent studies show that Type 2 diabetes is associated with a twofold increase in the risk of non-alcoholic fatty liver disease, a leading cause of chronic liver disease. Individuals with non-alcoholic steatohepatitis, a more advanced stage of non-alcoholic fatty liver disease, are specifically at risk of developing fibrosis/cirrhosis (end-stage liver disease) and hepatocellular carcinoma; therefore, identifying individuals (with Type 2 diabetes) who are likely to develop hepatic complications is paramount. In the present clinical review, we discuss the potential impact of non-alcoholic fatty liver disease diagnosis on Type 2 diabetes, and the putative risk factors for developing non-alcoholic steatohepatitis and non-alcoholic steatohepatitis fibrosis. We highlight the limitations of currently used tools in non-alcoholic fatty liver disease diagnosis and staging, and provide an insight into future developments in the field. We present an example of a non-alcoholic fatty liver disease screening protocol and discuss the therapeutic options currently available to our patients.

Molecular cloning, expression analysis and functional characterization of chicken cytochrome P450 27A1: A novel mitochondrial vitamin D3 25-hydroxylase.

Vitamin D3 is hydroxylated by cytochrome P450 (CYP) before exerting biological effects. The chicken CYP involved in vitamin D3 25-hydroxylation has yet to be cloned, and little is known about its functional characteristics, tissue distribution, and cellular expression. We identified a novel, full-length CYP27A1 gene cloned from chicken hepatocyte cDNA that encodes a putative protein of 518 amino acids. Swiss modeling revealed that chicken CYP27A1 has a classic open-fold form. Multisequence homology alignment determined that CYP27A1 contains conserved motifs for substrate recognition and binding. Quantitative real-time PCR analysis in 2-mo-old Partridge Shank broilers demonstrated that CYP27A1 mRNA levels were highest in the liver, followed by the thigh muscles, the breast muscles, and kidneys. The transcripts of CYP27A1 in breast muscles were significantly higher in males than in females. A subcellular localization analysis demonstrated that CYP27A1 was mainly expressed in the mitochondria. In vitro enzyme assays suggested that recombinant CYP27A1 hydroxylates vitamin D3 at the C-25 position to form 25-hydroxyvitamin D3 (25(OH)D3). The Km and Vmax values for CYP27A1-dependent vitamin D3 25-hydroxylation were estimated to be 4.929 µM and 0.389 mol min-1 mg-1 protein, respectively. In summary, these results suggest that CYP27A1 encodes a mitochondrial CYP that plays an important physiologic role in the 25-hydroxylation of vitamin D3 in chickens, providing novel insights into vitamin D3 metabolism in this species.

Follow up of aerobic capacity in children affected by severe acute respiratory syndrome.

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the aerobic capacity of children 3 years after they were diagnosed with severe acute respiratory syndrome (SARS). METHODS: Twenty-seven patients who completed both pulmonary function and maximal aerobic capacity tests at 6 and 15 months after the acute illness were invited to return for reassessment. RESULTS: Twenty-one patients (median age 18.2 years, interquartile range (IQR) 16.5-19.7) completed all investigations at 36 months. Pulmonary function was normal in all patients. Maximal aerobic capacity, peak oxygen pulse (peak VO(2) ) and ventilatory anaerobic threshold showed significant improvements compared with values measured at 6 months in both boys and girls. In girls, ventilatory efficiency (ventilatory equivalents for oxygen and carbon dioxide) and perfusion of the lungs (end-tidal partial carbon dioxide pressure) had not increased further compared with the values measured at 15 months. Although peak VO(2) improved further at 36 months in patients with or without persistent radiological abnormalities, the values were 68% (IQR 50-84) and 74% (IQR 60-99), respectively, of those for normal control subjects. CONCLUSIONS: There were improvements in aerobic capacity at 36 months in children affected by SARS; however, the measured values remained suboptimal.

Does reverse mentoring work in the NHS: a feasibility study of clinicians in practice.

OBJECTIVE: To assess the risks and benefits of reverse mentoring of consultants by junior doctors. DESIGN: A feasibility study divided into two phases: first a semistructured interview where performance of participating consultants was assessed by junior doctors and then a second phase allowing for feedback to be given on a one-to-one basis. Data collected through questionnaires with free text questions and Likert scores. SETTING: Tertiary teaching hospital in the UK. PARTICIPANTS: Six junior doctors (66.6% male, age range 31-40 years) and five consultants (80% male, age range 35-65 years and consultants for 5-20 years). INTERVENTION: Reverse mentoring session. MAIN OUTCOME MEASURE: The concerns and/or benefits of the process of reverse mentoring. Confidence was assessed in 7 domains: clinical practice, approach to juniors, approachability, use of technology, time management, strengths and areas for improvement using Likert scales giving a total out of 35. RESULTS: The most common concerns cited were overcoming the hierarchical difference and a selection bias in both mentors and mentees. However, no participant experienced this hierarchical difference through the reverse mentoring process and no relationships were negatively affected. Mentors became more confident in feeding back to seniors (23 vs 29 out of 35, p=0.04) most evident in clinical practice and areas to improve (3 vs 4 out of 5, p=0.041 and 3 vs 5 out of 5, p=0.041, respectively). CONCLUSION: We present the first study of reverse mentoring in an NHS clinical setting. Initial concerns with regard to damaged relationships and hierarchical gradients were not experienced and all participants perceived that they benefited from the process. Reverse mentoring can play a role in engaging and training future leaders at junior stages and provide a means for consultants to receive valuable feedback from junior colleagues.

Epidemiology of obstructive sleep apnoea syndrome in Chinese children: a two-phase community study.

OBJECTIVE: To determine the prevalence and risk factors of obstructive sleep apnoea syndrome (OSAS) in Chinese children using a two-phase community-based study design. METHODS: Children from 13 primary schools were randomly recruited. A validated OSAS screening questionnaire was completed by their parents. Children at high risk of OSAS and a randomly chosen low-risk group were invited to undergo overnight polysomnographic study and clinical examination. The the sex-specific prevalence rate was measured using different cutoffs (obstructive apnoea hypopnoea index ≥ 1, ≥ 1.5, ≥ 3 and ≥ 5 and obstructive apnoea index ≥ 5) and risk factors associated with OSAS were evaluated with logistic regression. RESULTS: 6447 completed questionnaires were returned (out of 9172 questionnaires; 70.3%). 586 children (9.1%; 405 boys and 181 girls) children belonged to the high-risk group. A total of 619 (410 and 209 from the high and low-risk group, respectively) subjects underwent overnight polysomnagraphy. Depending on the cutoffs, the prevalence rate of childhood OSAS varied from 4.8% to 40.3%. Using the International Criteria of Sleep Disorders version II, the OSAS prevalence for boys and girls was 5.8% and 3.8%, respectively. Male gender, body mass index z-score and increased adenoid and tonsil size were independently associated with OSAS. CONCLUSIONS: The prevalence rate of OSAS in children was contingent on the cutoff used. The inclusion of symptoms as a part of the diagnostic criteria greatly reduced the prevalence. A further prospective and outcome study is needed to define a clinically significant diagnostic cutoff for childhood OSAS.

Rapid identification and differentiation of Gram-negative and Gram-positive bacterial bloodstream infections by quantitative polymerase chain reaction in preterm infants.

OBJECTIVE: To evaluate the usefulness of the Gram-specific probe-based quantitative polymerase chain reaction test for rapid detection and differentiation of Gram-negative and Gram-positive bacterial bloodstream infection in preterm infants. DESIGN: Cross-sectional study. SETTING: University-affiliated Level III neonatal intensive care unit. PATIENTS: Preterm infants with clinical features suggestive of late-onset infection. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: In addition to the full sepsis screen, 0.5 mL of EDTA blood was collected aseptically for Gram-specific quantitative polymerase chain reaction evaluation. The results were analyzed with respect to outcomes of bacterial culture in blood and other body fluids, including peritoneal and cerebrospinal fluids. The diagnostic utilities of the quantitative polymerase chain reaction were determined. A total of 218 suspected infection episodes were investigated, of which 42 episodes were culture positive and 176 were culture negative. For Gram-negative infection, the quantitative polymerase chain reaction test correctly identified 19 of 22 episodes, and the sensitivity and specificity were 86.4% and 99.0%, respectively. For Gram-positive infection, the test correctly identified 14/19 episodes, and the sensitivity and specificity were 73.7% and 98.5%. The remaining one episode was Candida albicans septicemia. None of the episodes with positive quantitative polymerase chain reaction test were classified into the wrong Gram stain category. More importantly, despite negative blood culture in five infants suffering from intra-abdominal sepsis (peritonitis [n = 4] and hepatosplenic abscess [n = 1]), the quantitative polymerase chain reaction test could detect the Gram-specific category of causative organisms in blood. CONCLUSIONS: The Gram-specific quantitative polymerase chain reaction test is reliable and highly specific for rapid identification and differentiation of Gram-negative and Gram-positive bloodstream and intra-abdominal infections. The result could be made available within 5 hrs after the specimen reaches the laboratory. A positive test is able to "rule in" bacterial bloodstream infection before blood culture results become available, and serves as a guide to predict the virulence of the causative organism according to its Gram-specific category so that critical patients can be targeted for intensive treatment.

Blood pressure is elevated in children with primary snoring.

OBJECTIVES: To compare ambulatory blood pressure (ABP) in nonoverweight, prepubertal children with and without primary snoring (PS), and to investigate whether PS is a part of the dose-response relationship between sleep-disordered breathing (SDB) and BP in children. STUDY DESIGN: This was a cross-sectional community-based study involving 190 children age 6 to 13 years. Each participant underwent an overnight sleep study and ABP monitoring after completing a validated sleep symptoms questionnaire. Individual systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial BP were calculated for wake and sleep periods. Subjects were hypertensive if mean SBP or DBP was > 95th percentile (relative to sex and height) of reference. RESULTS: A total of 56 nonsnoring controls, 46 children with PS, 62 children with an apnea-hypopnea index (AHI) of 1 to 3, and 26 children with an AHI > 3 were identified. The daytime and nighttime BP increased across the severity spectrum of SDB. The dose-response trends for the proportion of subjects with nighttime systolic and diastolic hypertension also were significant. Nighttime DBP was significantly higher in the children with PS compared with controls after adjusting for age, sex, and body mass index. CONCLUSIONS: PS was demonstrated to be an aspect of the dose-response relationship between SDB and BP in children and should not be considered completely benign.

Transient increase in intraocular pressure during a dose-tapering regime of systemic dexamethasone in preterm infants.

PURPOSE: To determine the intraocular pressure (IOP) profile during and after systemic dexamethasone treatment in preterm very low birth weight (VLBW; <1500 g) infants. DESIGN: A cohort study at a university-affiliated tertiary neonatal center. PARTICIPANTS: Twenty-seven VLBW infants who received a 3-week dose-tapering course of systemic dexamethasone for treatment of bronchopulmonary dysplasia were consecutively enrolled over a period of 32 months. METHODS: Intraocular pressure was assessed using a handheld tonometer immediately before (week 0), during (weeks 1 and 3), and after (weeks 5, 7, and 9) commencement of the dexamethasone course. The mixed-effects models were used to evaluate the longitudinal IOP measurements at different time points. MAIN OUTCOME MEASURES: To assess the magnitude and duration of increase in IOP during systemic corticosteroid treatment. RESULTS: The IOP at week 1, while the infants were receiving the maximum dose of dexamethasone (0.6 mg/kg/day), was significantly higher than (1) the pretreatment IOP at week 0 (mean [+/- standard deviation]: 19.7 [+/-3.7] vs. 16.4 [+/-3.7] mmHg, respectively) (P<0.0001), (2) the IOP when the infants were receiving the minimum dose of dexamethasone (0.15 mg/kg/day) at week 3 (19.7 [+/-3.7] vs. 15.8 [+/-4.3] mmHg) (P<0.0001), and (3) the IOP after the dexamethasone course had been stopped between week 5 and week 9 (19.7 [+/-3.7] vs. 16.0 [+/-4.0], 15.3 [+/-3.5], and 14.5 [+/-3.3] mmHg for weeks 5, 7, and 9, respectively) (P<0.0001 for all comparisons). In contrast, there was no significant difference between the pretreatment IOP (week 0) and IOP at week 3, 5, 7, or 9 (P = 0.07-0.62) and in the IOP between week 3 and week 5, 7, or 9 (P = 0.27-0.75). CONCLUSIONS: The use of a dose-tapering regime of dexamethasone is associated with transient increase of IOP. As IOP was significantly raised during the high-dose but not the low-dose treatment period, we speculate that the physiologic or stress dose of corticosteroids commonly advocated for treatment of serious neonatal conditions should be safe and unlikely to cause significant ocular hypertension in preterm infants.

Effects of neonatal oxytocin treatment on aggression and neural activities in mandarin voles.

Neonatal manipulation of oxytocin (OT) has long-term effects on behavior and physiology. Here we test the hypothesis that neonatal OT treatment can affect the subsequent expression of intrasexual aggression partly by reprogramming the neural activities of relevant brain regions. To test this hypothesis, mandarin voles (Lasiopodomys mandarinus) received OT or isotonic saline treatment within 24 h of birth. At about 75 days of age, aggressive behaviors and Fos expression in different brain regions were tested. The results indicate that the (1) level of intrasexual aggression was higher and other social contact was lower in SAL-treated sexually naïve males than in females and; (2) OT-treated females showed a greater increase in aggressive behaviors and Fos expression only after exposure to a male than SAL-treated females, but there were no significant changes in aggressive behaviors in males. These results demonstrate a sexual difference in aggression, and that neonatal exposure to OT may increase aggression in female mandarin voles. These effects may be based on changes in neural activities of relevant brain regions including the bed nucleus of the stria terminalis (BNST), lateral septal nucleus (LS), medial preoptic area (MPOA), the paraventricular nucleus of the hypothalamus (PVN), supraoptic nucleus (SON), mediodorsal thalamic nucleus (MD), ventromedial nucleus of hypothalamic (VMH), the medial amygdala (MeA) and central amygdala (CeA).

Fetal methylmercury exposure as measured by cord blood mercury concentrations in a mother-infant cohort in Hong Kong.

This study was designed to examine newborn infants in Hong Kong prenatally exposed to levels of methylmercury considered to increase risk of neurotoxic effects and to examine subject characteristics that modify the degree of prenatal mercury exposure. Mercury concentrations in 1057 sets of maternal and cord blood samples and 96 randomly selected maternal hair samples were measured. Subject characteristics were measured or collected by questionnaire. Of the 1057 cord blood samples collected only 21.6% had mercury concentrations less than 29 nmol/L (5.8 micro g/L). Median maternal hair mercury concentration was 1.7 ppm. The geometric mean cord to maternal blood mercury ratio was 1.79 to 1. Increasing maternal fish consumption and maternal age were found to be associated with increased cord blood mercury concentrations. Marine fish consumption increased cord blood mercury concentrations more than freshwater fish (5.09%/kg vs 2.86%/kg). Female babies, maternal alcohol consumption and increasing maternal height were associated with decreased cord blood mercury concentrations. Pregnant women in Hong Kong consume large amounts of fish and as a result, most of their offspring have been prenatally exposed to moderately high levels of mercury. In this population, pregnant women should choose freshwater over marine fish and limit fish consumption.

Sputum induction in children with asthma: a tertiary-center experience.

Our aims were 1) to report on our experience with sputum induction (SI), and 2) to determine predictive factors associated with successful SI in asthmatic children. Children with asthma attending the chest clinic of a university teaching hospital between October 2003-December 2004 were recruited. They completed a visual analogue scale for symptom severity, and underwent physical examination, skin-prick test, exhaled nitric oxide (eNO) measurement, spirometry, and SI. Adequate sputum contained <50% squamous epithelial cells. Predictors for successful induction were evaluated using multivariate logistic regression analysis. One hundred and thirty subjects were recruited. The median age was 11.25 years (range 7.0-17.5), and the majority were boys (75%). All except two had normal percent predicted forced expired volume in 1 sec (>80%). The median eNO was 48.95 ppb. Sputum induction was successful in 93 subjects (74.5%). Sore throat and chest discomfort occurred in 20 (15%) and 8 (6%) subjects, respectively, and the procedure was prematurely terminated in three cases. Levels of eNO were found to be a predictor for successful induction (area under the ROC (receiver operator characteristics curves) curve, 0.634). Sputum induction was well-tolerated by all subjects, and was successful in 74.5% of cases. Exhaled nitric oxide may be a useful marker for successful induction.

Chinese nursing students' attitudes toward traditional Chinese medicine.

In this study, we examined Chinese nursing students' attitudes toward and use of traditional Chinese medicine (TCM). Survey questionnaires were distributed to 439 nursing students, 263 of whom (60%) returned them. Of the respondents, 92% had used TCM, while 48% had used TCM at least once during the previous year. Forty-five percent of respondents reported positive attitudes toward TCM use, 52% had neutral attitudes, and only 3% reported negative attitudes. The majority of respondents (76%) reported no change in their attitude toward TCM after studying nursing. Mean scores related to the adequacy of the current curriculum in TCM training and the state of respondents' TCM knowledge were generally low. Of the respondents who had used TCM during the past year, the most common use was for upper respiratory tract infection. The most common type of TCM used by respondents was herbal tea or soup. Final-year nursing students were more likely to have used TCM during the previous year, report they would like more courses on TCM, and consult Western medicine physicians before using TCM; they were also less likely to develop more negative attitudes toward TCM after studying nursing.

Are your hands clean enough for point-of-care electrolyte analysis?

AIM: To investigate clinically significant analytical interference in point-of-care electrolyte analysis caused by contamination of blood specimens with hand disinfectant. METHODS: Six different hand hygiene products were added separately to heparinised blood samples in varying amounts as contaminant. The contaminated samples were analysed by three different blood gas and electrolyte analysers for assessing interference on measured whole blood sodium and potassium concentrations. RESULTS: There were significant analytical interferences caused by hand hygiene product contamination that varied depending on the combination of disinfectant and analyser. Small amounts of Microshield Antibacterial Hand Gel contamination caused large increases in measured sodium concentration. Such effect was much greater compared with the other five products tested, and started to occur at much lower levels of contamination. There was a trend towards lower sodium results in blood samples contaminated with Hexol Antiseptic Lotion (Hexol), the hand hygiene product that we used initially. Apart from AiE Hand Sanitizer, all the other hand disinfectants, especially Hexol, significantly elevated the measured potassium concentration, particularly when a direct ion-selective electrode method was used for measurement. CONCLUSIONS: Hand disinfectant products can significantly interfere with blood electrolyte analysis. Proper precautions must be taken against contamination since the resultant errors can adversely affect the clinical management of patients.

Treatment of recurrent thyroid cysts by injection of tetracycline or minocycline.

We analyzed the effects of tetracycline hydrochloride or minocycline hydrochloride sclerotherapy on 66 recurrent thyroid cysts. All were hemorrhagic lesions except one serous cyst; cytologic study showed all were benign. On average, three treatments were given until resolution or the patient became unavailable for follow-up. The cumulative frequency of cyst disappearance was 33%, 45%, 52%, and 59% after 1, 2, 3, and 4 treatments. Five additional patients had cyst resolution after six to 19 treatments, and the serous lesion did not resolve. Cysts requiring more than two treatments were larger at presentation than those resolving after one or two treatments. Side effects in 179 treatments were local pain lasting ten to 20 minutes in 4.5%, radiated pain lasting one to two hours in 4.5%, fatigue lasting one to two days in 3.9%, and a febrile sensation lasting one to two days in 2.8%. Hemorrhagic thyroid cysts can usually be cured by repeated tetracycline or minocycline sclerotherapy with tolerable side effects.

Shark CNS myelin contains four polypeptides related to the PNS protein Po of higher classes.

The relationship between the proteins of shark central nervous system (CNS) myelin and those of myelin from higher classes has been investigated using antibodies raised against a 31,500 molecular weight polypeptide from shark myelin. The antibodies cross-reacted with 3 shark CNS polypeptides apart from the original antigen, with 2 major polypeptides from shark peripheral nervous system myelin, with the Po protein from chicken and sheep peripheral nervous system myelin, but with none of the components of bovine CNS myelin. It appears that the oligodendroglial cells of the shark synthesize a protein closely related to the Po protein produced by Schwann cells of vertebrate classes above and including chondrichthytes.