[Identification and genetic analysis of new mutations in EYA1 gene of BOS syndrome]

Objective: To analyze the clinical manifestations of a patient with branchiootic syndrome(BOS) and her families and to carry out genetic testing in order to specify the biological pathogenesis. Methods: Clinical data of the patient and her families were collected. Genomic DNA in the peripheral blood of the proband and her family members was extracted. All exons of 406 deafness-related susceptible genes as well as their flanking regions were sequenced by high-throughput sequencing, and the mutation sites of the proband and her parents were validated by Sanger sequencing. Results: There were nine members in three generations, of whom four presented with hearing loss, preauricular fistula and branchial fistula which met the diagnostic criteria of BOS. Proband and her mother presented with auricle malformation and inner ear malformation. And no one had abnormalities in the kidneys of all the patients. Pedigree analysis revealed that the mode of inheritance in the family was consistent with the autosomal dominant pattern. Mutational analysis showed that all the affected patients detected a heterozygous frameshift variation c.1255delT in the EYA1 gene, which had not been reported. Genotype and phenotype were co-isolated in this family. Such a frameshift variation produced a premature termination codon, thereby causing premature termination of translation (p.C419VFS*12). ACMG identified that the mutation was pathogenic. This mutation was novel and not detected in controls. A heterozygous missense variation mutation c.403G>A(p.G135S) in EYA1 gene was also detected in three members of this family. ACMG identified that the mutation clinical significance was uncertain. However, two of whom were normal, which seemed the disease was not caused by this mutation in this family. Conclusions: A novel frameshift mutation in EYA1(c.1255delT) is the main molecular etiology of BOS in the Chinese family. This study expands the mutational spectrum of EYA1 gene. The clinical manifestations are heterogeneous among patients in this family. The diagnosis of BOS should combine gene tests with clinical phenotypes analysis.

[Analysis of genetic characteristics in two Chinese children of type Ⅱ Waardenburg syndrome]

Objective: To screen and analyze the mutations of MITF gene in two children of type Ⅱ Waardenburg syndrome (WS2) from different families in Yunnan,China,and to explore the possible molecular pathogenesis. Methods: With informed consent, medical history collection, physical examinations, audiological evaluation, and high resolution computer tomography (HRCT) scan of temporal bone were performed on the two WS2 probands and their family members. Genomic DNA was extracted from peripheral blood of all individuals. The coding regions including all exons, part of introns and promoters of MITF, PAX3, SOX10, SNAI2, END3, ENDRB, and KITLG genes were sequenced by high-throughput sequencing. According to the results of high-throughput sequencing, pathogenic mutations detected in the probands and their parents were verified by Sanger sequencing. Results: The proband 1 carried c.641_643delGAA mutation in the 7th exon of MITF gene, which was a frame-shift mutation resulting in an amino acid change of p.214delR. It was a de novo mutation as the parents of proband 1 showed no variation on this site. The proband 2 carried heterozygous loss of the large fragment ranging from exon 1 to exon 9 of MITF gene, which defected the function of MITF protein. Conclusion: Genetic examinations provide important evidence for diagnosis of Waardenburg syndrome. Heterozygous mutation c.641_643delGAA and heterozygous loss of the large fragment ranging from exon 1 to exon 9 of MITF gene might be the molecular pathogenesis of the two WS2 probands in this study.

[A comparative study on diagnosis of silicosis by digital and high kV film-screen chest radiography]

Objective: To explore the feasibility of soft copy image of chest digital radiography (DR(SC)) in pneumoconiosis diagnosis by observing the reading effect of DR(SC) and comparing it with high kV film-screen chest radiography (FSR(HkV)) . To provide a basis for the establishment of a regional information network platform for pneumoconiosis diagnosis. Methods: A total of 119 miners who were exposed to silica dust and engaged in copper or lead-zinc mining were collected by the Third People's Hospital of Yunnan from October 2017 to August 2019. The pulmonary X-ray findings of DRSC and FSR(HkV) in each case were independently judged and diagnosed by three experienced diagnostic physicians, and the final decision was made according to the consensus of most doctors. The consistency of the two imaging methods was analyzed by observing the main small opacity shape, the overall density, the range of distribution, the aggregation of the small opacity and the big opacity, and the diagnosis stage. Results: there were 118 males and 1 female with an average age of 46.21 years. Average exposure time 7.38 years. The pulmonary X-ray findings of 113 cases with two imaging methods were mainly the round small opacity of p,q and r,but the reticular irregular opacity were not prominent, Only one case of FSR(HkV) judgment p shape and DR(SC) judgment q shape were observed, The coincidence rate was 99.12% (112/113) . huger opacity were observed in the other 6 cases. The coincidence rate was 95.51% (4/89) between pneumoconiosis-free and stageⅠ, and there was no significant difference between stageⅡand stage Ⅲ (30/30, P>0.05) . Conclusion: The x-ray findings of Silicosis with small round shadow in lung can be used by DR(SC) in diagnosis and staging.

[The technique of retaining part of the external auditory canal posterior wall with epitympanoplasty in soft wall reconstruction treating middle ear cholesteatoma]

Objective:To investigate the surgical treatment of cholesteatoma of the middle ear. Method:A retrospective analysis of patients from June 2013 to July 2016 diagnosed as cholesteatoma. 137 ears were divided into A group (retaining part of the external auditory canal posterior wall with epitympanoplasty in soft wall reconstruction for 75 ears) and B group (canal wall down mastoidotympanoplasty for 62 ears). the extent and damage of cholesteatoma were observed, comparing the time of dry ear and epithelial postoperative, the incidence of complications such as dizziness and hearing changes. Result:compared with B group, the postoperative dry ear time, epithelial time and hearing improvement in the A group were obviously improved, and the incidence of vertigo after operation was decreased, and the anatomical and physiological functions of the external auditory canal were protected. Conclusiont:The technique of retaining part of the external auditory canal posterior wall with epitympanoplasty in soft wall reconstruction is conductive to the removal of lesions and normal anatomical and physiological protection to external auditory canal, can prevent the forming of the abstraction pocket effectively and the recurrence of cholesteatoma, has clinical and practical value.

Antidepressant use during pregnancy and the risk of attention-deficit/hyperactivity disorder in the children: a meta-analysis of cohort studies

BACKGROUND

Evidence for the relationship between antidepressant use during pregnancy and the risk of attention-deficit/hyperactivity disorder (ADHD) in the children is conflicting.

OBJECTIVE

To assess the association between fetal exposure to antidepressant drugs and the subsequent development of ADHD.

SEARCH STRATEGY

A systematic literature search was conducted in PubMed, EMBASE, PsycINFO, and CINAHL databases to identify relevant cohort studies published from inception until October 2017.

SELECTION CRITERIA

Cohort studies, identifying children with ADHD diagnosis and linking antidepressant use during pregnancy in their mothers.

DATA COLLECTION

Two reviewers independently abstracted data and assessed study quality.

MAIN RESULTS

The literature search identified six relevant cohort studies with association between antidepressant exposure during pregnancy and the risk of ADHD in children [hazard ratio (HR) 1.34; 95% confidence interval (CI) 1.14-1.57]. However, the association was not statistically significant when the reference group was mothers with psychiatric disorders not treated during pregnancy (HR 0.96; 95% CI 0.76-1.2; n = 2 studies). Moreover, preconception exposure to antidepressants was significantly associated with increased risk of ADHD (HR 1.82; 95% CI 1.54-2.15; n = 3 studies).

CONCLUSIONS

The significant association between antidepressant exposure during pregnancy and ADHD in the children can be partially explained by confounding by indication. Given the low number of included studies, further studies with prospective designs that use validated measurements and controls for important confounders are needed to verify our findings.

TWEETABLE ABSTRACT

Antidepressant use during pregnancy may be not associated with ADHD in the offspring.

[Clinical value of health-related quality of life evaluation in community patients with hepatitis B]

Chronic hepatitis B (CHB) is a major infectious disease which threatens people's health around the world. Health-related quality of life (HRQoL) has become an important index for evaluating the treatment and prognosis of patients with CHB. Many studies abroad have shown that the HRQoL of patients with CHB is influenced by various factors. Disease severity, clinical symptoms, and low self-efficacy are important influencing factors for patients' quality of life. Anti-viral therapy, proper physical therapy, or psychological intervention can significantly improve the HRQoL of community CHB patients, and HRQoL is even significantly improved in patients undergoing liver transplantation one year ago. These studies provide valid evidence for antiviral therapy for hepatitis B patients and liver transplantation techniques from the psychological level. At present, there still lacks studies on HRQoL of CHB patients in China. This article summarizes the measurement tools for HRQoL widely used in recent years in China and foreign countries, reviews the research advances in HRQoL in community patients with CHB, and discusses the perspectives for future studies.

[Minimally invasive surgical techniques of cochlear implantation withround window pathways in young children]

Objective:To discuss the minimally invasive surgical techniques and the effect of cochlear implantation with round window pathways in young children(≤3 years).Method:One hundred and sixty patients with bilateral profound sensorineural hearin loss received MED-EL cochlear implantation,including 144 cases of normal middle and inner ear,4 cases of Mondini deformity,12 cases of large vestibular aqueduct syndrome.Result:Of 160 patients underwent CIs,148 patients were performed with round window pathways,the rate was 92.5%. Iit's difficult to exposure round window in 12 patients,performing from promontory.All electrodes of 158 cases with unilateral CI and 2 cases with bilateral CI were implanted successfully,in which the CI went normally and electrode array were protected well.All implant devices had worked normally and all patients had performed well during an average follow-up period of 8 month-3 years.Post-operatively complications of cerebrospinal fluid leakage,facial nerve injury haven't been found.Conclusion:Cochlear implantation could be performed in patients wit with round window pathways,and it is a safe and effective way in young children.

Computed tomography findings of hepatic veno-occlusive disease caused by Sedum aizoon with histopathological correlation

This study investigated the value of computed tomography (CT) in the diagnosis and treatment of hepatic veno-occlusive disease (HVOD) caused by Sedum aizoon (SA). The clinical manifestations, treatment results, imaging findings, and histological findings of the liver were analyzed in 39 patients with HVOD caused by SA. Hepatomegaly, liver dysfunction, abdominal effusion, and geographic density changes on liver CT scans were found in all 39 patients. The pathological findings of histological liver examination included swelling and point-like necrosis of liver cells, significant expansion and congestion of the sinuses, endothelial swelling, and wall thickening with incomplete lumen occlusion of small liver vessels. CT geographic density changes were confirmed by histological examination of the liver in 18 patients. Sixteen patients with small amounts of ascites that started within 4 weeks of treatment recovered completely or significantly improved after symptomatic and supportive treatment. However, only 43.75% of the patients with larger amounts of ascites improved following symptomatic and supportive treatment. In conclusion, liver CT examination is a valuable, safe, and noninvasive tool for the diagnosis of HVOD caused by SA. In selected cases, liver CT examination may replace liver biopsy and histological analysis.

Intestinal microbiota and innate immunity-related gene alteration in cirrhotic rats with liver transplantation

BACKGROUND

The present study investigated the alteration of intestinal microbiota, innate immunity-related genes, and bacterial translocation in rats with cirrhosis and liver transplantation.

METHODS

Specific pathogen-free Sprague-Dawley rats were randomized into 4 groups: (1) normal controls (N); (2) liver cirrhosis (LC); (3) normal control groups with liver transplantation (LTN); and (4) liver cirrhosis with liver transplantation (LTC). We examined plasma endotoxin, bacterial tacslocation, denaturing gradient gel electrophoresis (DGGE) profile of intestinal mucosa-associated bacteria, abundance of key bacterial populations, and expression of innate immunity-related gene.

RESULTS

The LTC and LC group, showed higher endotoxin levels (1.08±0.73 EU/mL and 0.74±0.70 EU/mL, respectively) than the N group (0.27±0.13 EU/mL; P<.05). the incidence of bacterial translocation (BT) to liver and mesenteric lymph nodes (MLN), and the number of total bacteria were increased significantly in the LTC and LC groups compared with the N group (P<.05). The counts of Lactobacilli and Bacteroides were lower, whereas Enterobacteria were higher in the LC than the N group (P<.05). Mucins (MUC2, MUC3) and Toll-like receptors (TLR2, TLR4) messenger RNA (mRNA) expression were significantly higher in the LC and LTC groups than the N group (P<.05). The marked difference between the groups in the overall structure of the bacterial community was also generated by DGGE profiles.

CONCLUSION

Liver cirrhosis disturbs intestinal microbiota and innate immunity-related genes, which contributes to endotoxemia and bacterial translocation. These had not completely recovered in cirrhotic rats until 1 month after orthotopic liver transplantation.

Studies on the chemical constituents of Psoralea corylifolia L

A new isoflavone, corylinin (1), along with six known compounds, isopsoralen (2), psoralen (3), sophoracoumestan A (4), neobavaisoflavone (5), daidzin (6) and uracil (7), have been isolated from the dried fruits of Psoralea corylifolia L. The structure of 1 was established as 7,4'-dihydroxy-3'-[(E)-3,7-dimethyl-2,6-octadienyl]isoflavone on the basis of the spectroscopic methods. Structures of the known compounds were identified by comparison of the literature.

Cys-tRNACys formation and cysteine biosynthesis in methanogenic archaea: two faces of the same problem?

Aminoacyl-tRNA (transfer RNA) synthetases are essential components of the cellular translation machinery as they provide the ribosome with aminoacyl-tRNAs. Aminoacyl-tRNA synthesis is generally well understood. However, the mechanism of Cys-tRNACys formation in three methanogenic archaea ( Methanocaldococcus jannaschii, Methanothermobacter thermautotrophicus and Methanopyrus kandleri) is still unknown, since no recognizable gene for a canonical cysteinyl-tRNA synthetase could be identified in the genome sequences of these organisms. Here we review the different routes recently proposed for Cys-tRNACys formation and discuss its possible link with cysteine biosynthesis in these methanogenic archaea.

Genomics and the evolution of aminoacyl-tRNA synthesis

Translation is the process by which ribosomes direct protein synthesis using the genetic information contained in messenger RNA (mRNA). Transfer RNAs (tRNAs) are charged with an amino acid and brought to the ribosome, where they are paired with the corresponding trinucleotide codon in mRNA. The amino acid is attached to the nascent polypeptide and the ribosome moves on to the next codon. Thus, the sequential pairing of codons in mRNA with tRNA anticodons determines the order of amino acids in a protein. It is therefore imperative for accurate translation that tRNAs are only coupled to amino acids corresponding to the RNA anticodon. This is mostly, but not exclusively, achieved by the direct attachment of the appropriate amino acid to the 3'-end of the corresponding tRNA by the aminoacyl-tRNA synthetases. To ensure the accurate translation of genetic information, the aminoacyl-tRNA synthetases must display an extremely high level of substrate specificity. Despite this highly conserved function, recent studies arising from the analysis of whole genomes have shown a significant degree of evolutionary diversity in aminoacyl-tRNA synthesis. For example, non-canonical routes have been identified for the synthesis of Asn-tRNA, Cys-tRNA, Gln-tRNA and Lys-tRNA. Characterization of non-canonical aminoacyl-tRNA synthesis has revealed an unexpected level of evolutionary divergence and has also provided new insights into the possible precursors of contemporary aminoacyl-tRNA synthetases.

Cation-dependent stability of subtilisin

Subtilisin BPN' contains two cation binding sites. One specifically binds calcium (site A), and the other can bind both divalent and monovalvent metals (site B). By binding at specific sites in the tertiary structure of subtilisin, cations contribute their binding energy to the stability of the native state and increase the activation energy of unfolding. Deconvoluting the influence of binding sites A and B on the inactivation rate of subtilisin is complicated, however. This paper examines the stabilizing effects of cation binding at site B by using a mutant of subtilisin BPN' which lacks calcium site A. Using this mutant, we show that calcium binding at site B has relatively little effect on stability in the presence of moderate concentrations of monovalent cations. At [NaCl] =100 mM, site B is >or=98% occupied with sodium, and therefore its net occupancy with a cation varies little as subtilisin is titrated with calcium. Exchanging sodium for calcium results in a 5-fold decrease in the rate of inactivation. In contrast, because of the high selectivity of site A for calcium, its occupancy changes dramatically as calcium concentration is varied, and consequently the inactivation rate of subtilisin decreases approximately 200-fold as site A becomes saturated with calcium, irrespective of the concentration of monovalent cations.

Stabilizing mutations and calcium-dependent stability of subtilisin

Stability is a property of subtilisin which has proven particularly amenable to enhancement via random mutagenesis and screening, yet the effects of most stabilizing mutations are not understood in structural and energetic detail. This paper seeks to explain the longstanding observation that stabilizing mutations are usually calcium-dependent in their stabilizing effect, irrespective of their proximity to the calcium binding sites. Stabilizing mutations in subtilisin fall into one of three classes. The largest class of mutations stabilize only in the presence of excess calcium. A smaller number of mutations stabilize independently of [calcium], and a few mutations stabilize only in the presence of chelating agents, such as EDTA. This study compares the effects of mutations from each class when introduced into subtilisin BPN' and two calcium-free versions of subtilisin. The calcium-dependent effects of mutations can be explained by considering subtilisin to be in conformational equilibrium between two structurally similar but energetically distinct states: N and N*. The equilibrium from the N* to the N state can be altered either by calcium binding to site A or by mutation. Mutations which stabilize only in the presence of calcium stabilize the N state relative to N*. Mutations which stabilize only in the presence of chelants stabilize the N* state relative to N. As a byproduct of this analysis, we have developed a hyperstable variant of subtilisin whose inactivation at high temperature in the presence of EDTA is 10(5) times slower than wild-type subtilisin.

Genomics and the evolution of aminoacyl-tRNA synthesis

Translation is the process by which ribosomes direct protein synthesis using the genetic information contained in messenger RNA (mRNA). Transfer RNAs (tRNAs) are charged with an amino acid and brought to the ribosome, where they are paired with the corresponding trinucleotide codon in mRNA. The amino acid is attached to the nascent polypeptide and the ribosome moves on to the next codon. Thus, the sequential pairing of codons in mRNA with tRNA anticodons determines the order of amino acids in a protein. It is therefore imperative for accurate translation that tRNAs are only coupled to amino acids corresponding to the RNA anticodon. This is mostly, but not exclusively, achieved by the direct attachment of the appropriate amino acid to the 3'-end of the corresponding tRNA by the aminoacyl-tRNA synthetases. To ensure the accurate translation of genetic information, the aminoacyl-tRNA synthetases must display an extremely high level of substrate specificity. Despite this highly conserved function, recent studies arising from the analysis of whole genomes have shown a significant degree of evolutionary diversity in aminoacyl-tRNA synthesis. For example, non-canonical routes have been identified for the synthesis of Asn-tRNA, Cys-tRNA, Gln-tRNA and Lys-tRNA. Characterization of non-canonical aminoacyl-tRNA synthesis has revealed an unexpected level of evolutionary divergence and has also provided new insights into the possible precursors of contemporary aminoacyl-tRNA synthetases.

Sterols in blood of normal and Smith-Lemli-Opitz subjects

Smith-Lemli-Opitz syndrome (SLOS) is a hereditary disorder in which a defective gene encoding 7-dehydrocholesterol reductase causes the accumulation of noncholesterol sterols, such as 7- and 8-dehydrocholesterol. Using rigorous analytical methods in conjunction with a large collection of authentic standards, we unequivocally identified numerous noncholesterol sterols in 6 normal and 17 SLOS blood samples. Plasma or erythrocytes were saponified under oxygen-free conditions, followed by multiple chromatographic separations. Individual sterols were identified and quantitated by high performance liquid chromatography (HPLC), Ag(+)-HPLC, gas chromatography (GC), GC-mass spectrometry, and nuclear magnetic resonance. As a percentage of total sterol content, the major C(27) sterols observed in the SLOS blood samples were cholesterol (12;-98%), 7-dehydrocholesterol (0.4;-44%), 8-dehydrocholesterol (0.5;-22%), and cholesta-5,7,9(11)-trien-3beta-ol (0.02;-5%), whereas the normal blood samples contained <0.03% each of the three noncholesterol sterols. SLOS and normal blood contained similar amounts of lathosterol (0.05;-0.6%) and cholestanol (0.1;-0.4%) and approximately 0.003;-0.1% each of the Delta(8), Delta(8(14)), Delta(5,8(14)), Delta(5,24), Delta(6,8), Delta(6,8(14)), and Delta(7,24) sterols. The results are consistent with the hypothesis that the Delta(8(14)) sterol is an intermediate of cholesterol synthesis and indicate the existence of undescribed aberrant pathways that may explain the formation of the Delta(5,7,9(11)) sterol. 19-Norcholesta-5,7,9-trien-3beta-ol was absent in both SLOS and normal blood, although it was routinely observed as a GC artifact in fractions containing 8-dehydrocholesterol. The overall findings advance the understanding of SLOS and provide a methodological model for studying other metabolic disorders of cholesterol synthesis.

Progestins block cholesterol synthesis to produce meiosis-activating sterols

The resumption of meiosis is regulated by meiosis-preventing and meiosis-activating substances in testes and ovaries. Certain C29 precursors of cholesterol are present at elevated levels in gonadal tissue, but the mechanism by which these meiosis-activating sterols (MAS) accumulate has remained an unresolved question. Here we report that progestins alter cholesterol synthesis in HepG2 cells and rat testes to increase levels of major MAS (FF-MAS and T-MAS). These C29 sterols accumulated as a result of inhibition of Delta24-reduction and 4alpha-demethylation. Progesterone, pregnenolone, and 17alpha-OH-pregnenolone were potent inhibitors of Delta24-reduction in an in vitro cell assay and led to the accumulation of desmosterol, a Delta5,24 sterol precursor of cholesterol. A markedly different effect was observed for 17alpha-OH-progesterone, which caused the accumulation of sterols associated with inhibition of 4alpha-demethylation. The flux of 13C-acetate into lathosterol and cholesterol was decreased by progestins as measured by isotopomer spectral analysis, whereas newly synthesized MAS accumulated. The combined evidence that MAS concentrations can be regulated by physiological levels of progestins and their specific combination provides a plausible explanation for the elevated concentration of MAS in gonads and suggests a new role for progestins in fertility.

Meiosis-activating sterol and the maturation of isolated mouse oocytes

This study was carried out to examine the effects of the meiosis-activating C(29) sterol, 4,4-dimethyl-5 alpha-cholesta-8,14, 24-trien-3 beta-ol (FF-MAS), on mouse oocyte maturation in vitro. Cumulus cell-enclosed oocytes (CEO) and denuded oocytes (DO) from hormonally primed, immature mice were cultured 17-18 h in minimum essential medium (MEM) containing 4 mM hypoxanthine plus increasing concentrations of FF-MAS. The sterol induced maturation in DO with an optimal concentration of 3 microg/ml but was without effect in CEO, even at concentrations as high as 10 microg/ml. Some stimulation of maturation in hypoxanthine-arrested CEO was observed when MEM was replaced by MEMalpha. Interestingly, the sterol suppressed the maturation of hypoxanthine-arrested CEO in MEM upon removal of glucose from the medium. FF-MAS also failed to induce maturation in DO when meiotic arrest was maintained with dibutyryl cAMP (dbcAMP). The rate of maturation in FF-MAS-stimulated, hypoxanthine-arrested DO was slow, as more than 6 h of culture elapsed before significant meiotic induction was observed, and this response required the continued presence of the sterol. Although the oocyte took up radiolabeled lanosterol, such accumulation was restricted by the presence of cumulus cells. In addition, lanosterol failed to augment FSH-induced maturation and was even inhibitory at a high concentration. Moreover, the downstream metabolite, cholesterol, augmented the inhibitory action of dbcAMP on maturation in both CEO and DO. Two inhibitors of 14 alpha-demethylase, ketoconazole, and 14 alpha-ethyl-5 alpha-cholest-7-ene-3 beta, 15 alpha-diol that can suppress FF-MAS production from lanosterol failed to block consistently FSH-induced maturation. These results confirm the stimulatory action of FF-MAS on hypoxanthine-arrested DO but do not support a universal meiosis-inducing function for this sterol.

Aberrant pathways in the late stages of cholesterol biosynthesis in the rat. Origin and metabolic fate of unsaturated sterols relevant to the Smith-Lemli-Opitz syndrome

Minor aberrant pathways of cholesterol biosynthesis normally produce only trace levels of abnormal sterol metabolites but may assume major importance when an essential biosynthetic step is blocked. Cholesta-5,8-dien-3beta-ol, its Delta(5,7) isomer, and other noncholesterol sterols accumulate in subjects with the Smith-Lemli-Opitz syndrome (SLOS), a severe developmental disorder caused by a defective Delta(7) sterol reductase gene. We have explored the formation and metabolism of unsaturated sterols relevant to SLOS by incubating tritium-labeled Delta(5,8), Delta(6, 8), Delta(6,8(14)), Delta(5,8(14)), and Delta(8) sterols with rat liver preparations. More than 60 different incubations were carried out with washed microsomes or the 10,000 g supernatant under aerobic or anaerobic conditions; some experiments included addition of cofactors, fenpropimorph (a Delta(8);-Delta(7) isomerase inhibitor), and/or AY-9944 (a Delta(7) reductase inhibitor). The tritium-labeled metabolites from each incubation were identified by silver ion high performance liquid chromatography on the basis of their coelution with unlabeled authentic standards, as free sterols and/or acetate derivatives. The Delta(5,8) sterol was converted slowly to cholesterol via the Delta(5,7) sterol, which also slowly isomerized back to the Delta(5,8) sterol. The Delta(6,8) sterol was metabolized rapidly to cholesterol by an oxygen-requiring pathway via the Delta(7,9(11)), Delta(8), Delta(7), and Delta(5,7) sterols as well as by an oxygen-independent route involving initial isomerization to the Delta(5,7) sterol. The Delta(8) sterol was partially metabolized to Delta(5,8), Delta(6,8), Delta(7,9(11)), and Delta(5,7,9(11)) sterols when isomerization to Delta(7) was blocked.The combined results were used to formulate a scheme of normal and aberrant biosynthetic pathways that illuminate the origin and metabolic fate of abnormal sterols observed in SLOS and chondrodysplasia punctata.

Synthesis of [3alpha-3H]cholesta-5,8-dien-3beta-ol and tritium-labeled forms of other sterols of potential importance in the Smith-Lemli-Optiz syndrome

Five unsaturated sterols relevant to the Smith-Lemli-Opitz syndrome have been prepared in high radiochemical purity with a tritium label at the 3alpha position. Swern oxidation of cholesta-5,8-dien-3beta-ol and other unlabeled C27 sterols afforded the corresponding 3-ketosteroids, and reduction with tritiated NaBH4 gave the desired 3alpha-3H sterols, with double bonds at the delta(5,8), delta(5,8(14)), delta(6,8), delta(6,8(14)), and delta8 positions. High radiochemical purity of the tritiated sterols was demonstrated by normal phase, reversed phase, and silver-ion (Ag+) high-performance liquid chromatography (HPLC). In the course of this work, we developed a medium-pressure variant of Ag+-HPLC for purifying radiolabeled samples, documented significant isotopic fractionation of the 3alpha-tritiated sterols and their acetates on Ag+-HPLC, and discovered unexpected effects of a delta(8(14)) bond on the conformation of 3-keto-delta5-steroids. The synthetic and analytical methodologies described herein should provide a sound basis for investigating the origin and metabolism of sterols involved in the Smith-Lemli-Opitz syndrome and in late stages of cholesterol biosynthesis.

[A preliminary study on hepatitis E virus antibody IgG and IgM for the diagnosis of acute hepatitis E]

OBJECTIVE

To evaluate the significance of hepatitis E virus antibody (anti-HEV) IgG and IgM for the diagnosis of acute hepatitis E.

METHODS

Acute phase sera from a total of 143 patients with sporadic hepatitis E in 7 cities of China were determined for anti-HEV IgM and IgG by using an enzyme-linked immunosorbent assay (EIA). 359 serial sera of 56 patients with hepatitis E and 68 serial sera of 4 rhesus macaques experimentally infected with hepatitis E virus (HEV) were also detected for anti-HEV IgG and IgM.

RESULTS

In the 143 patients the positive rate of anti-HEV IgG was 100.0%, which was significantly higher than that of anti-HEV IgM (73.4%, 105/143). 97.2% of anti-HEV IgG positive patients had a titer over 1:40. The positive rate of anti-HEV IgM increased with the titer of anti-HEV IgG in sera. It was 0% (0/4), 44.4% (8/18) and 80.2% (97/121), respectively in patients with the anti-HEV IgG titer of 1:20, 1:40 and >or=1:80 (P < 0.001). All the anti-HEV IgM positive patients were also anti-HEV IgG positive. No patients were found to be anti-HEV IgM positive alone. Anti-HEV IgG was detected as early as 2 days after onset of the disease, with a cumulative positive seroconversion rate of 100% by 1 month. The negative seroconversion rate of anti-HEV IgG increased with course of the disease and 43.3% of the patients lost their anti-HEV IgG by 6 months after illness. Though anti-HEV IgM also seroconverted at the same time as anti-HEV IgG, its cumulative positive seroconversion rate was only 71.4% and declined rapidly. Up to 37.5% of anti-HEV IgM positive patients became negative by 1 month after onset. Similar antibody responses were observed in 4 rhesus macaques experimentally infected with HEV.

CONCLUSION

It is suggested that as a result of the poor sensitivity of currently available anti-HEV IgM EIA kits, anti-HEV IgG will be a more reliable marker for the diagnosis of acute hepatitis E as compared with anti-HEV IgM.

Rapid folding of calcium-free subtilisin by a stabilized pro-domain mutant

In vitro folding of mature subtilisin is extremely slow. The isolated pro-domain greatly accelerates in vitro folding of subtilisin in a bimolecular reaction whose product is a tight complex between folded subtilisin and folded pro-domain. In our studies of subtilisin, we are trying to answer two basic questions: why does subtilisin fold slowly without the pro-domain and what does the pro-domain do to accelerate the folding rate? To address these general questions, we are trying to characterize all the rate constants governing individual steps in the bimolecular folding reaction of pro-domain with subtilisin. Here, we report the results of a series of in vitro folding experiments using an engineered pro-domain mutant which is independently stable (proR9) and two calcium-free subtilisin mutants. The bimolecular folding reaction of subtilisin and proR9 occurs in two steps: an initial binding of proR9 to unfolded subtilisin, followed by isomerization of the initial complex into the native complex. The central findings are as follows. First, the independently stable proR9 folds subtilisin much faster than the predominantly unfolded wild-type pro-domain. Second, at micromolar concentrations of proR9, the subtilisin folding reaction becomes limited by the rate at which prolines in the unfolded state can isomerize to their native conformation. The simpliest mechanism which closely describes the data includes two denatured forms of subtilisin, which form the initial complex with proR9 at the same rate but which isomerize to the fully folded complex at much different rates. In this model, 77% of the subtilisin isomerizes to the native form slowly and the remaining 23% isomerizes more rapidly (1.5 s-1). The slow-folding population may be unfolded subtilisin with the trans form of proline 168, which must isomerize to the cis form during refolding. Third, in the absence of proline isomerization, the rate of subtilisin folding is rapid and at [proR9] </= 20 microM is limited by the rate at which the proR9 forms a collision complex with unfolded subtilisin. Without proline isomerization, the rate of the isomerization of the initial collision complex to the folded complex is >3 s-1. The implications of these results concerning why subtilisin folds slowly without the pro-domain are discussed.

An improved synthesis of (20R,22R)-cholest-5-ene-3beta,20,22-triol, an intermediate in steroid hormone formation and an activator of nuclear orphan receptor LXR alpha

Asymmetric dihydroxylation of (20(22)E)-cholesta-5,20(22)-dien-3beta-ol acetate (2a), prepared from pregnenolone, gave a 1:1 mixture (67% yield) of (20R,22R)-cholest-5-ene-3beta,20,22-triol 3-acetate (3a) and its 20S,22S isomer 3b. Highly purified 3a and 3b were obtained by semipreparative silver ion high performance liquid chromatography. Saponification of 3a and 3b gave (20R,22R)-cholest-5-ene-3beta,20,22-triol (4a) and its 20S,22S isomer 4b. This simple approach provided the natural isomer 4a more efficiently than previously described chemical or enzymatic syntheses. Full 1H and 13C nuclear magnetic resonance data were presented for triols 4a and 4b and their synthetic precursors. Side-chain conformations of 2a, its 20(22)Z isomer, 4a, and 4b were studied by molecular mechanics and nuclear Overhauser effect difference spectroscopy.

Stabilizing the subtilisin BPN' pro-domain by phage display selection: how restrictive is the amino acid code for maximum protein stability?

We have devised a procedure using monovalent phage display to select for stable mutants in the pro-domain of the serine protease, subtilisin BPN'. In complex with subtilisin, the pro-domain assumes a compact structure with a four-stranded antiparallel beta-sheet and two three-turn alpha-helices. When isolated, however, the pro-domain is 97% unfolded. These experiments use combinatorial mutagenesis to select for stabilizing amino acid combinations at a particular structural locus and determine how many combinations are close to the maximum protein stability. The selection for stability is based on the fact that the independent stability of the pro-domain is very low and that binding to subtilisin is thermodynamically linked to folding. Two libraries of mutant pro-domains were constructed and analyzed to determine how many combinations of amino acids at a particular structural locus result in the maximum stability. A library comprises all combinations of four amino acids at a structural locus. Previous studies using combinatorial genetics have shown that many different combinations of amino acids can be accommodated in a selected locus without destroying function. The present results indicate that the number of sequence combinations at a structural locus, which are close to the maximum stability, is small. The most striking example is a selection at an interior locus of the pro-domain. After two rounds of phagemid selection, one amino acid combination is found in 40% of sequenced mutants. The most frequently selected mutant has a deltaG(unfolding) = 4 kcal/mol at 25 degrees C, an increase of 6 kcal/mol relative to the naturally occurring sequence. Some implications of these results on the amount of sequence information needed to specify a unique tertiary fold are discussed. Apart from possible implications on the folding code, the phage display selection described here should be useful in optimizing the stability of other proteins, which can be displayed on the phage surface.

[Computerized transformation of the cardiotocographic paper record to its digital equivalent for computerised analysis]

OBJECTIVE

To analyze cardiotocograph by computer, the tracings recorded in paper form must first be converted into their digital equivalent. We developed a method by which this process may be performed.

METHODS

Paper recordings were first scanned using a conventional flat bed scanner to obtain a digital image. Each image was firstly corrected for rotational misalignment error during scanning and, sceondly the grid was removed by performing logistic contrast enhancement to leave the discrete fetal heart rate and tocographic tracings. The method was validated by comparing differences between the fetal heart rate obtained from the paper record with that directly obtained from the fetal monitor.

RESULTS

Forty recordings were analyzed. The mean difference per recording between the actual and derived values ranged from -0.26(-)-1.26 beats per minute. The 95% confidence interval for the pooled differences between the derived and actual fetal heart rate values was--7-5 beats per minute.

CONCLUSION

By using the techniques described in this paper, it is now possible to convert the large number of paper records available so that they can be analyzed by computerized cardiotocograph interpreters.

Sterols affecting meiosis: novel chemical syntheses and the biological activity and spectral properties of the synthetic sterols

4,4-Dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol (I) from human follicular fluid and 4,4-dimethyl-5alpha-cholesta-8,24-dien-3beta-ol (II) from bull testes have been reported to activate meiosis in mouse oocytes (Byskov et al., 1995. Nature. 374: 559-562). Described herein are new chemical syntheses of I, II, and the delta8(14),24 analog XXII. A critical step in these syntheses was a remarkably high yield side chain oxidation of 3beta-acetoxy-4,4-dimethyl-5alpha-cholest-8(14)-en-15-one to the corresponding C24 24-hydroxy compound VI. Oxidation of VI to the aldehyde, followed by Wittig olefination gave 3beta -acetoxy4,4-dimethyl-5alpha-cholesta-8(14),24-dien-15- one. Reduction with sodium borohydride to the 15beta-hydroxysteryl ester, dehydration with sulfuric acid in CHCl3, and saponification furnished I in high purity. Reduction of VI with sodium borohydride to the 15-hydroxysteroid followed by dehydration gave 3beta-acetoxy-4,4-dimethyl-5alpha-chola-8,14-dien-24-o l. Hydrogenation over Raney nickel gave the monounsaturated delta8(14) and delta8 compounds. Oxidation to the corresponding aldehydes followed by Wittig olefination and saponification gave II and XXII. Chromatographic, mass spectral, and 1H and 13C nuclear magnetic resonance spectral data have been presented for the synthetic sterols and their derivatives. I, II, XXII, and their delta8,14 and delta7,14 analogs, at 3 microg per ml, caused a resumption of meiosis in mouse oocytes in the presence of hypoxanthine (3.5 mM). Under the same conditions, delta5 and delta5,7 sterols were inactive.

[Dynamics of anti-HEV ORF2, ORF3, IgM and IgG in serial sera of patients with hepatitis E and their clinical significance]

OBJECTIVE

To study the dynamics of anti-HEV ORF2, ORF3, IgM and IgG in serial sera of patients with hepatitis E.

METHODS

Anti-HEV was detected in serial sera of 52 patients, by an enzyme-linked immunosorbent assay (EIA) based on two synthetic peptides separated or combined from open reading frame (ORF) 2 and 3 of HEV genome.

RESULTS

Both anti-ORF2 and anti-ORF3 in serum were at the highest levels in early acute phase of the disease, and declined gradually with the course, especially anti-ORF3. The sensitivity of the EIA using both ORF2 and ORF3 peptides was higher than that of either alone. The positive rates of anti-HEV IgM and anti-HEV IgG were separately 71.1% (32/45) and 97.8% (44/45) within 15 days after onset, then decreased more dramatically in IgM than in IgG with the course.

CONCLUSION

Both ORF2 and ORF3 proteins should be used for the development of anti-HEV EIA kit. It seems to be more specific in anti-HEV IgM and more sensitive in anti-HEV IgG as a diagnostic marker of hepatitis E.

Engineering the independent folding of the subtilisin BPN' pro-domain: correlation of pro-domain stability with the rate of subtilisin folding

The 77-amino acid pro-domain greatly accelerates the in vitro folding of subtilisin in a bimolecular reaction whose product is a tight complex between folded subtilisin and folded pro-domain. In this complex the pro-domain has a compact structure with a four-stranded antiparallel beta-sheet and two three-turn alpha-helixes. When isolated from subtilisin, however, the pro-domain is 97% unfolded even under optimal folding conditions. The instability of the isolated pro-domain suggests that there may be a thermodynamic linkage between the stability of the pro-domain and its ability to facilitate subtilisin folding. On the basis of the X-ray crystal structure of the pro-domain subtilisin complex, we have designed stabilizing mutations in three areas of the pro-domain: alpha-helix 23-32 (E32Q), beta-strands 35-51 (Q40L), and alpha-helix 53-61 (K57E). These amino acid positions were selected because they do not contact subtilisin in the complex and because they appear to be in regions of the structure which are not well packed in the wild type pro-domain. Since none of the mutations directly contact subtilisin, their effects on the folding of subtilisin are linked to whether or not they stabilize a conformation of the pro-domain which promotes subtilisin folding. By sequentially introducing the three stabilizing mutations, the equilibrium for folding the pro-domain was shifted from 97% unfolded to 65% folded. By measuring the ability of these mutants to fold subtilisin, we are able to establish a correlation between the stability of the pro-domain and its ability to accelerate subtilisin folding. As the pro-domain is stabilized, the folding reaction becomes faster and distinctly biphasic. A detailed mechanism was determined for the double mutant, Q40L-K57E, which is 50% folded: P + Su if (30 800 M-1 s-1, 0.04 s-1) PSI if (0.07 s-1, <0.005 s-1) PS. PSI is an intermediate complex which accumulates in the course of the reaction, and PS is the fully folded complex. The more stable the pro-domain, the faster the folding reaction up to the point at which the isomerization of the intermediate into the fully folded complex becomes the rate-limiting step in the folding process.

An alternative synthesis of 4,4-dimethyl-5 alpha-cholesta-8,14,24-trien-3 beta-ol, an intermediate in sterol biosynthesis and a reported activator of meiosis and of nuclear orphan receptor LXR alpha

4,4-dimethyl-5 alpha-cholesta-8,14,24-trien-3 beta-ol, a sterol of current biological interest, has been synthesized in six steps from 3 beta-acetoxy-4,4-dimethyl-5 alpha-cholest-8(14)-en-15-one.

Sterol synthesis. A timely look at the capabilities of conventional and silver ion high performance liquid chromatography for the separation of C27 sterols related to cholesterol biosynthesis

Sterol intermediates in the biosynthesis of cholesterol have recently assumed a very prominent position in a number of important problems in medicine and biology. In studies of these matters, the separation and identification of the sterol intermediates present formidable challenges, a situation which does not appear to be generally appreciated. High performance liquid chromatography (HPLC) is a simple and rapid approach for the separation of the concerned compounds. Reversed phase HPLC is very commonly used for this purpose. In the present studies, we have evaluated the capabilities of reversed phase, normal phase, and silver ion HPLC for the separation of sterols. Using an extensive collection of authentic sterols, our studies indicate very limited capabilities of reversed phase and normal phase HPLC for the separation of C27 sterols differing in the number and location of olefinic double bonds. In contrast, silver ion HPLC provided remarkable separations of the same compounds, either as the free sterols or their acetate derivatives. These findings, coupled with the results of recent studies of the properties of the same compounds by gas chromatography and by nuclear magnetic resonance and mass spectroscopy, have important implications regarding current application of methodologies for the separation, identification, and quantitation of sterol intermediates in cholesterol biosynthesis as critical portions of investigations on a number of current and emerging problems in biology and medicine.

[A study on viremia in patients with hepatitis E]

Hepatitis E virus RNA (HEV RNA) was detected in 531 serial serum specimens collected from 62 hospitalized patients with hepatitis E by reverse transcription-nested polymerase chain reaction (RT-nPCR) setting two pairs of primer from open reading frame 1 (ORF1) to understand the process of HEV infection more thoroughly. Results showed that 71 percent of the patients were positive for HEV RNA. Thirty-two of them with 288 serial serum specimens were followed up for the whole process, and 24 cases (75%) were positive for HEV RNA, positive rates declined with the course of the disease and serum HEV RNA lasted for 20.6 days in average. Serum HEV RNA was kept positive in 36 of the 44 patients (81.8%) at the time their serum alanine aminotransferase (ALT) and serum total bilirubin began to lower, and anti-HEV was detected in 39 of them (88.6%). Proportion of HEV viremia and length of it had no direct relationship with serum ALT and levels of total serum bilirubin and anti-HEV.

The orphan nuclear receptor LXRalpha is positively and negatively regulated by distinct products of mevalonate metabolism

LXRalpha is an orphan member of the nuclear hormone receptor superfamily that displays constitutive transcriptional activity. We reasoned that this activity may result from the production of an endogenous activator that is a component of intermediary metabolism. The use of metabolic inhibitors revealed that mevalonic acid biosynthesis is required for LXRalpha activity. Mevalonic acid is a common metabolite used by virtually all eukaryotic cells. It serves as a precursor to a large number of important molecules including farnesyl pyrophosphate, geranylgeranyl pyrophosphate, cholesterol, and oxysterols. Inhibition of LXRalpha could be reversed by addition of mevalonic acid and certain oxysterols but not by other products of mevalonic acid metabolism. Surprisingly, the constitutive activity of LXRalpha was inhibited by geranylgeraniol, a metabolite of mevalonic acid. These findings suggest that LXRalpha may represent a central component of a signaling pathway that is both positively and negatively regulated by multiple products of mevalonate metabolism.

Engineering the independent folding of the subtilisin BPN' prodomain: analysis of two-state folding versus protein stability

In complex with subtilisin BPN', the 77 amino acid prodomain folds into a stable compact structure comprising a four-stranded antiparallel beta-sheet and two three-turn alpha-helices. When isolated from subtilisin, the prodomain is 97% unfolded even under optimal folding conditions. Traditionally, to study stable proteins, denaturing cosolvents or temperatures are used to shift the equilibrium from folded to unfolded. Here we manipulate the folding equilibrium of the unstable prodomain by introducing stabilizing mutations generated by design. By sequentially introducing three stabilizing mutations into the prodomain we are able to shift the equilibrium for independent folding from 97% unfolded to 65% folded. Spectroscopic and thermodynamic analysis of the folding reaction was carried out to assess the effect of stability on two-state behavior and the denatured state. The denatured states of single and combination mutants are not discernably different in spite of a range of DeltaGunfolding from -2.1 to 0.4 kcal/mol. Conclusions about the nature of the denatured state of the prodomain are based on CD spectral data and calorimetric data. Two state folding is observed for a combination mutant of marginal stability (DeltaG = 0). Evidence for its two-state folding is based on the observed additivity of individual mutations to the overall DeltaGunfolding and the conformity of DeltaGunfolding vs T to two-state assumptions as embodied in the Gibbs-Helmholz equation. We believe our success in stabilizing the two-state folding reaction of the prodomain originates from the selection of mutations with improved ability to fold subtilisin rather than selection for increase in secondary structure content. The fact that a small number of mutations can stabilize the independent folding of the prodomain implies that most of the folding information already exists in the wild-type amino acid sequence in spite of the fact that the unfolded state predominates.

An updated look at the analysis of unsaturated C27 sterols by gas chromatography and mass spectrometry

Gas chromatography-mass spectrometry (GC-MS) and GC are commonly used methods for the identification and quantitation of sterols from samples of biological origin. To investigate the utility and limitations of these methods, we have determined gas chromatographic mobilities and mass spectral properties of 5alpha-cholestan-3beta-ol and 26 unsaturated C27 sterols as their acetate and trimethylsilyl (TMS) ether derivatives by GC and GC-MS. The GC retention data showed that numerous sterols were essentially coeluted on capillary GC columns coated with either 5% phenyl-95% methyl polysiloxane or polyethylene glycol, although the peaks were more widely dispersed on the latter column. Mass spectra of many groups of sterol isomers were also quite similar. Sterol mixtures of any complexity are likely to contain coeluting components, and attempts to establish structures based on mass spectra that may represent a mixture of sterol isomers could easily lead to errors. Our results demonstrate that GC and GC-MS alone cannot generally be used for rigorous structure determinations of individual components in mixtures of unsaturated sterols. However, all but a few of the 26 sterols could be distinguished by their combined chromatographic mobilities on the two GC columns coupled with critical examination of their mass spectra. GC-MS analysis of appropriate sterol subclasses or preferably individual sterol components obtained by prior purification by other methods may provide valuable supporting evidence for the identification of sterol structures. Reliability of identification is dependent upon careful attention to GC and MS conditions, calibration of GC and MS data with authentic sterol standards, and consideration of possible decomposition under GC conditions and of the effect of overloading on GC retention times.

The RecD subunit of the RecBCD enzyme from Escherichia coli is a single-stranded DNA-dependent ATPase

We have expressed the RecD subunit of the RecBCD enzyme from Escherichia coli as a fusion protein with a 31-amino acid NH2-terminal extension including 6 consecutive histidine residues (HisRecD). The overexpressed fusion protein can be purified in urea-denatured form by metal chelate affinity chromatography. The mixture of renatured HisRecD protein and the RecB and RecC proteins has a high level of ATP-dependent nuclease activity with either single- or double-stranded DNA, enhanced DNA unwinding activity, enhanced ATP hydrolysis activity in the presence of a small DNA oligomer cosubstrate, and chi-cutting activity. These are all characteristics of the RecBCD holoenzyme. The HisRecD protein by itself hydrolyzes ATP in the presence of high concentrations of single-stranded DNA (polydeoxythymidine). The activity is unstable at 37 degrees C, but is measurable at room temperature (about 23 degrees C). The HisRecD has very little ATPase activity in the presence of a much shorter single-stranded DNA (oligodeoxy(thymidine)12). HisRecD hydrolyzes ATP more efficiently than GTP and UTP, and has very little activity with CTP. We also purified a fusion protein containing a Lys to Gln mutation in the putative ATP-binding site of RecD. This mutant protein has no ATPase activity, indicating that the observed ATP hydrolysis activity is intrinsic to the RecD protein itself.

Silver ion high pressure liquid chromatography provides unprecedented separation of sterols: application to the enzymatic formation of cholesta-5,8-dien-3 beta-ol

We report that silver ion HPLC provides remarkable separations of C27 sterols differing only in the number or location of olefinic double bonds. This technique has been extended to LC-MS, analysis of purified components by GC, GC-MS, and 1H NMR, and to its use on a semipreparative scale. The application of this methodology for the demonstration of the catalysis, by rat liver microsomes, of the conversion of 7-dehydrocholesterol to cholesta-5,8-dien-3 beta-ol is also presented.

Analysis of unsaturated C27 sterols by nuclear magnetic resonance spectroscopy

Complete 1H and 13C nuclear magnetic resonance (NMR) signal assignments have been established for 5 alpha-cholestan-3 beta-ol, 22 unsaturated C27 sterols, and their acetate derivatives. Assignments were made from a combination of 1D and 2D spectra and include stereochemical 1H assignments for the C-22 and C-23 protons of 5 alpha-cholesta-8,24-dien-3 beta-ol and other delta 24 sterols with a C8 side chain. At the temperature and concentration range described, chemical shifts were generally reproducible to +/- 0.01 ppm in 13C spectra and +/- 0.001 ppm in 1H spectra. Except for some overlapped or strongly coupled 1H resonances, chemical shifts are given to these precisions, which are an order of magnitude better than for most data given previously. Full 1H NMR data have been reported previously for only three of the 46 compounds, and 13C data were unavailable for many, including the previously undescribed cholesta-5,8(14)-dien-3 beta-ol. An extensive set of 1H-1H coupling constants for the unsaturated sterols indicated considerable conformational diversity, which was confirmed by molecular modeling. The conformational diversity together with other factors led to a complex pattern of 13C substituent-induced chemical shifts (SCS) that appeared to elude any simple empirical correlations with structure. By contrast, the 1H SCS correlated reasonably well with simple structural features. The high precision of the SCS revealed small but measurable effects of a double bond on 1H resonances up to 12 bonds away. Also discussed are the utility and limitations of NMR for the identification of unsaturated sterols, estimation of purity, and analysis of mixtures, with an emphasis on special problems encountered at a microgram level.