Overexpression of nerve growth factor in the heart alters ion channel activity and beta-adrenergic signalling in an adult transgenic mouse

1. The electrophysiological and pharmacological properties of cardiac myocytes from the hearts of adult transgenic mice engineered to overexpress nerve growth factor (NGF) in the heart were studied. 2. There was a 12% increase in the ventricular myocyte capacitance in NGF myocytes consistent with cardiac hypertrophy, and action potential duration at 90% repolarization (APD90) was prolonged by 142 % compared with wild-type (WT) myocytes. This was due, at least in part, to a decrease in the density of two K+ currents, Ito and IK(ur), which were significantly reduced in NGF mice with no change in their electrophysiological characteristics. We found no change in the current density or electrophysiological properties of the L-type Ca2+ current. 3. The effect on Ito and IK(ur) of TEA and 4-aminopyridine (4-AP) was not different in cells isolated from WT and NGF mice. The prolongation of APD observed in NGF cells was mimicked in WT cells by exposure to 1 mM 4-AP, which partially blocked Ito, completely blocked IK(ur) and increased APD90 by 157%. 4. The isoprenaline-induced increase in ICa was significantly smaller in NGF myocytes than in WT myocytes. This was not due to a decrease in beta-adrenergic receptor (beta-AR) density, as this was increased in NGF tissue by 55%. Analysis of beta-AR subtypes showed that this increase was entirely due to an increase in beta2-AR density with no change in beta1-ARs. 5. The response of the beta-AR-coupled adenylyl cyclase system to isoprenaline, Gpp(NH)p and forskolin was studied by measuring cAMP production. In NGF tissue, isoprenaline elicited a significantly smaller response than in WT myoyctes and this was not due to reduced adenylyl cyclase activity as the responses of NGF tissue to guanylylimidodiphosphate (Gpp(NH)p) and forskolin were unaffected. 6. In conclusion, the overexpression of NGF in the mouse heart resulted in a decrease in the current density of two K+ channels, which contributed to the prolongation of the cardiac action potential. Despite an increase in beta2-AR density in the hearts of the NGF mice, the response to isoprenaline was diminished, and this was due to an uncoupling of the beta-ARs from the intracellular signalling cascade. These potentially pathological changes may be involved in the occurrence of ventricular arrhythmias in cardiac hypertrophy and failure, and this mouse provides a novel model in which to study such changes.

[Clinico-pathological significance of microvessel density and VEGF expression in primary liver cancer]

OBJECTIVE

To evulate the clinico-pathological singnificance of intratumoral microvessel density (MVD) and VEGF expression in primary liver cancer (PLC).

METHODS

A retrospective study including 63 postoperative small PLC (diameter < 5 cm) patients was done. One group of 29 patients developed recurrence or metastasis within 2 years. The other group of 34 patients had no evidence of recurrence or metastasis within 2 years. Three PLC sections were taken from each patient, one for H. E. staining, the other two for VEGF and vascular endothelial cell immunohistochemical staining, respectively. MVD was counted by endothelial cells which were highlighted by Bio-UEA-I.

RESULTS

The MVD in patients with cancer recurrence or metastasis was (49.6 +/- 29.7) significantly greater than the other group (22.7 +/- 28.2) (P < 0.01). The positive rate of VEGF in cancer recurrence group was 86.2% (25/29), being significantly higher than the other group (47.1%) (P < 0.01). The stage of the tumor, the positive rate of satellite nodules and portal vein embolus were all significantly different between the 2 groups.

CONCLUSION

Besides tumor stage, satellite nodules and portal vein embolus, the MVD and VEGF expression are also of prognostic significance.

A common variant in PPP1R3 associated with insulin resistance and type 2 diabetes

Selected candidate genes have been analyzed in the Pima Indians of Arizona based on evidence that insulin resistance and type 2 diabetes have significant genetic determinants. An amino acid substitution at codon 905 of the glycogen-targeting subunit of type 1 protein phosphatase that regulates skeletal muscle glycogenesis was recently reported to be associated with changes in insulin action in Danish subjects. In addition to the variant at 905, we report here a novel substitution at codon 883 and common variant of an "ATTTA" element in the 3'-untranslated region (UTR) of the corresponding gene (PPP1R3). The 3'-UTR variant resembled the mRNA-destabilizing AT(AU)-rich elements (AREs) and resulted in a 10-fold difference in reporter mRNA half-life, was correlated with PPP1R3 transcript and protein concentrations in vivo, and was associated with insulin resistance and type 2 diabetes in the Pimas. The variant is more common in Pimas (0.56) than in Caucasians (0.40). Because of its apparent effect on expression of PPP1R3, it may, in part, contribute to the higher prevalence of type 2 diabetes in this Native American population.

[The evaluation of computer-aided simulating system in orthognathic surgery]

OBJECTIVE: The purpose of this study is to evaluate the reliabillty of computer-aided simulating system for orthognathic system. METHODS: 24 cases with dentofacial deformities were undergone treatment of orthognathic surgery.The presurgical cephalograms and profiles were input to the computer and were digitized.The simulated profiles and cephalometric analysis were obtained by the simulating system,and computer with the actual posttreatment cephalograms. RESULTS: The prodicted and actual posttreatment soft tissue line drawings were quite similar in all areas except for the lower lip region. CONCLUSION: In all cases,the actual images were judged more esthetic than the predicted images. It allayed the fears that the computer generated predictions were unrealistically and ideal.

Dietary supplementation of grape polyphenols and chronic ethanol administration on LDL oxidation and platelet function in rats

Polyphenolic compounds have been implicated as the active ingredients for the cardiac protective effect in red wine. We tested the effects of dietary supplementation of polyphenols from grape (GP) and chronic ethanol administration on low-density-lipoprotein (LDL) oxidation and platelet function in rats. Four groups of young male Sprague-Dawley rats were fed the following diets for 2 months: (I) a high fat Lieber-DeCarli liquid diet with an isocaloric amount of maltose, (II) with 5% ethanol (w/v), (III) with 5 mg/dL of GP, and (IV) ethanol plus GP. Platelet aggregation was induced by thrombin and phorbol myristate acetate (PMA) and LDL oxidation was induced by Cu2+. Chronic ethanol administration resulted in a significant increase in LDL oxidation and this effect was partially protected by supplementation with GP. Although platelet number was not affected by either ethanol or GP administration, platelet aggregation induced by thrombin was reduced in ethanol, GP and ethanol plus GP groups as compared to controls. On the other hand, platelet aggregation induced by PMA was not altered in any groups, suggesting that protein kinase C was not a causal factor for the reduction of aggregatory response induced by thrombin. These results show similar effects of ethanol and GP on platelet aggregation but different effects on LDL oxidation. It can be concluded that dietary supplementation with GP may exert partial protection on oxidative insults such as those elicited by chronic ethanol ingestion.

Interaction of the N-ethylmaleimide-sensitive factor with AMPA receptors

Glutamate receptors mediate the majority of rapid excitatory synaptic transmission in the central nervous system (CNS) and play important roles in synaptic plasticity and neuronal development. Recently, protein-protein interactions with the C-terminal domain of glutamate receptor subunits have been shown to be involved in the modulation of receptor function and clustering at excitatory synapses. In this paper, we have found that the N-ethylmaleimide-sensitive factor (NSF), a protein involved in membrane fusion events, specifically interacts with the C terminus of the GluR2 and GluR4c subunits of AMPA receptors in vitro and in vivo. Moreover, intracellular perfusion of neurons with a synthetic peptide that competes with the interaction of NSF and AMPA receptor subunits rapidly decreases the amplitude of miniature excitatory postsynaptic currents (mEPSCs), suggesting that NSF regulates AMPA receptor function.

[A technique of constructing human chromosomal band-specific probe pools using degenerate oligonucleotide primer]

OBJECTIVE

To establish a rapid and efficient technique of constructing human chromosomal band specific probe pools and their libraries.

METHODS

A modified method of combining chromosome microdissection with degenerate oligonucleotide primed PCR(DOP-PCR) was used. 3p23-p26, 3q21-q22 and 4p12- p16 band from human chromosomes were microdissected and amplified as probe pools. The origins of the PCR products were determined by chromosome fluorescence in situ hybridization. The PCR products and pUC19 were digested by Xho I and Sal I respectively, and linke up. The DH5alpha were transformed by the recombinated vectors as the specific band libraries. The inserts were digested by EcoR I and Hind III, then measured by electrophoretic analysis. And the copies of inserts were identified by in situ bacterial colony hybridization with genomic DNA.

RESULTS

All the three probe pools showed the special yellow-green signals in their microdissection responsible bands. The sizes of DOP-PCR products ranged from 300bp to 1800bp. 3q21-q22 probe pool generated about 1.2 x 10(4) clones. The average size of inserts was about 420bp by analysis of 30 positive clones. The rate of single-copy and low-repeated sequences was about 81%(178/220), while the rate of middle-repeated and high- repeated sequences was about 19%(42/220).

CONCLUSION

The results proved that the modified microdissection combining DOP-PCR technique provided a simple and efficient method to construct the human chromosome band-specific probe pools and might contribute to gene cloning and complete sequencing of human genome.

Changes in IP3R1 and SERCA2b mRNA levels in the gerbil brain after chronic ethanol administration and transient cerebral ischemia-reperfusion

Despite epidemiological studies indicating a positive relationship between alcohol and stroke, little is known with regard to effect of chronic alcohol on neuronal injury after stroke. In this study, we examined the effect of chronic ethanol on mRNA levels of sarcoplasmic or endoplasmic Ca2+-ATPase (SERCA2b) and inositol 1,4, 5-triphosphate receptor (IP3R1) in gerbils subjected to global cerebral ischemia induced by ligation of both common carotid arteries. Gerbils were given daily by intragastric intubation either a liquid diet containing ethanol (4 g/kg) or the same diet with an isocaloric amount of sucrose for 35 days. They were subsequently subjected to a 5 min ischemic insult followed by reperfusion for 48 h. In agreement with other studies, ischemic insult caused significant decreases (P<0.05) in mRNA levels of both IP3R1 and SERCA2b in the hippocampal CA1 region but not in the dentate gyrus. Nevertheless, despite a significant (P<0.05) decrease in SERCA2b mRNA in the Purkinje neurons, chronic ethanol did not alter the expression of this mRNA species in the hippocampal CA1 neurons nor did it alter the decrease in SERCA2b mRNA due to cerebral ischemic insult. Since IP3R1 and SERCA2b are key mediators for regulation of intracellular Ca2+ stores, the decrease in SERCA2b mRNA but not IP3R1 mRNA in cerebellar neurons may be an important mechanism underlying alteration of calcium homeostasis and cerebellar degeneration upon chronic ethanol consumption.

Camptothecin-20-PEG ester transport forms: the effect of spacer groups on antitumor activity

An improved synthesis of the hindered PEG-camptothecin diester transport form has been achieved using the Mukaiyama reagent. We have also assessed the effect of changing the electronic configuration of the (d-position of PEG-camptothecin transport forms on the rates of hydrolysis of the pro-moiety, and attempted to correlate these differences to efficacy in two animal models. In addition to the simple substitution of N for O, other synthetic modifications of these atoms were accomplished by employing heterobifunctional linker groups. The half lives by disappearance (rates of hydrolysis) of the transport forms in buffer and rat plasma were determined. It was established that anchimeric assistance to hydrolytic breakdown of the pro-moiety occurs in a predictable manner for some of these compounds. Results for the new derivatives in a P388 murine leukemic model and HT-29 human colorectal xenograft study are also presented. The use of a glycine linker group was found to provide similar efficacy in rodent models to that of simple camptothecin 20-PEG ester, and displayed enhanced pharmacokinetics.

[Study of physiological parameters of velopharyngeal function by nasopharyngeal fibroscope]

OBJECTIVE

Velopharyngeal incompetency (VPI) could be found in certain healthy people when some vowels were produced. Since neither asophia nor organic deformity do they have, it should be considered as physiological VPI. VPI which exists commonly in patients with cleft palate is also an unsatisfactory manifestation after palatoplasty. In order to distinguish between physiological VPI and pathological VPI in patient with cleft palate and establish an objective criterion, it is necessary to assess the occurrence and extent of VPI in healthy people.

METHODS

The velopharyngeal function of 890 subjects with normal speech was studied dynamically by nasopharyngeal fiberscope (NPF). Two vowels /i/ and /u/ were examined. The rates of velopharyngeal incompetence (RVPI) of vowel /i/ and /u/ were analyzed.

RESULTS

VPI was found in 117 (13.15%) when vowel /i/ was produced. VPI was occurred in 100 (11.24%) when /u/ was produced. The RVPI mean of vowel /i/ is 11.285% +/- 7.248 in 112 subjects, while that of /u/ is 9.066% +/- 6.162 in 96. No significant difference was obtained in age or sex.

CONCLUSION

It can be used to evaluate the velopharyngeal function after palatoplasty as physiological parameters.

Quantitation of MoMuLV envelope protein on the cell surface

The envelope glycoprotein (Env) of Moloney murine leukemia virus (MoMuLV) is proteolytically processed and transported to the cell surface where it can be incorporated into budding virions. Cell surface Env is frequently detected using an indirect immunofluorescence assay and fluorescence-activated cell sorting (FACS). We found that the detection of Env in this manner requires the expression of the MoMuLV receptor (ATRC-1) on the cell surface, and the level of envelope protein detected correlates with the level of receptors expressed on the cell. In addition, Env detection corresponds to the Env protein's ability to bind to its receptor and can be competed out by the addition of a truncated form of the Env protein. These data suggest that Env detected on the cell surface by the FACS assay is protein that has rebound to its receptor after being secreted or shed, rather than actual surface-expressed protein. In contrast, a combined immunoprecipitation and biotinylation assay detected equal amounts of Env on the surface of both receptor-lacking and receptor-expressing cell lines. The immunoprecipitation-biotinylation assay is therefore a more appropriate method for detecting surface expression of the MoMuLV envelope protein.

Species-specific and sequence-specific recognition of the dG-rich strand of telomeres by yeast telomerase

A gel mobility shift assay was developed to examine recognition of yeast telomeres by telomerase. An RNase-sensitive G-rich strand-specific binding activity can be detected in partially purified yeast telomerase fractions. The binding activity was attributed to telomerase, because it co-purifies with TLC1 RNA and telomerase activity over three different chromatographic steps and because the complex co-migrates with TLC1 RNA when subjected to electrophoresis through native gels. Analysis of the binding specificity of yeast telomerase indicates that it recognizes the G-rich strand of yeast telomeres with high affinity and specificity. The K d for the interaction is approximately 3 nM. Single-stranded G-rich telomeres from other species, such as human and Tetrahymena, though capable of being extended by yeast telomerase in polymerization assays at high concentrations, bind the enzyme with at least 100-fold lower affinities. The ability of a sequence to be bound tightly by yeast telomerase in vitro correlates with its ability to seed telomere formation in vivo. The implications of these findings for regulation of telomerase activity are discussed.

Age differences in the expression of metabotropic glutamate receptor 1 and inositol 1,4,5-trisphosphate receptor in mouse cerebellum

Age differences in the expression of cerebellar metabotropic glutamate receptor 1 (mGluR1) and inositol 1,4,5-trisphosphate receptor (IP3R) were investigated using male C57BL/6NNIA mice 5, 15 and 24 months of age. In situ hybridization for mGluR1 mRNA in the granule cell layer indicated significantly higher mRNA levels in the 24-month-old group as compared to the 5- and 15-month-old groups. However, mRNA levels of individual Purkinje neurons did not show age differences. Western blot analysis using antibody against the predominant isoform, mGluR1a, showed a decline in protein levels in the 24-month-old animals. In situ hybridization for IP3R type 1 mRNA in Purkinje neurons showed a slight but not significant decline in the 24-month-old group. Further assay of [3H]IP3 binding with cerebellar membranes showed significant reduction in Bmax values in the 15- and 24-month-old groups as compared to the 5-month-old group but Kd values were not changed. The decrease in mGluR1a receptor protein together with reduction in IP3R binding sites may play an important role in the decline in cerebellar functions with increasing age.

Patterns of excitation-contraction coupling in arterioles: dependence on time and concentration

We sought to understand the excitation-contraction coupling process in arterioles. KCl or phenylephrine (PE) was applied via the superfusion solution or by brief pulsatile ejections from a micropipette onto unpressurized arterioles (in vitro) from either the guinea pig small intestine or hamster cheek pouch. With either mode of application, KCl caused depolarizations that were tightly and predictably correlated with subsequent constrictions (electromechanical coupling). In contrast, the relationship between membrane potential and vasoconstriction in response to phenylephrine was dependent on both stimulus duration and agonist concentration. Application of short pulses of PE (< 1 s) produced mechanical responses that were dominated by pharmacomechanical coupling (i.e., they were not associated with changes in membrane potential). With longer PE stimuli, electromechanical coupling became more important and dominated microvessel responses. We conclude that adequate understanding of the signaling process in microvessels requires a consideration of both concentration and duration of application. Both the mode and duration of agonist application affect the relative degree of electromechanical or pharmacomechanical coupling in response to a vasomotor stimulus. These observations have important implications for intracellular and intercellular signaling.

Molecular pharmacology of UK-118, 434-05, a permanently charged amlodipine analog

We studied the effects of UK-118, 434-05, a permanently charged form of amlodipine, on recombinant smooth muscle and cardiac L-type calcium channels to determine the distinct modulatory properties of the ionized form of amlodipine. We found that the short distance between the permanent charge group and the active dihydropyridine (DHP) ring of UK-118, 434-05 reduces the potency of this compound as an inhibitor of smooth muscle (alpha(1c-b)) L-type channels, and is similar to the effects of other charged DHP derivatives on cardiac (alpha(1c-a)) L-type channels. However, we found surprisingly that the tonic block of cardiac (alpha(1c-a)) L-type channels was more pronounced than the tonic block of smooth muscle (alpha(1c-b)) L-type channels. This result contrasts with the previously reported subunit-specificity of neutral DHP compounds, and suggests that interactions between the amlodipine charge group and site(s) on the L-type channel alpha1 subunit distinguish the action of charged from neutral DHPs and may contribute to amlodipine's unique pharmacological profile.

Tau-like proteins in the nervous system of goldfish

This report describes the presence of a group of tau-like proteins (TLPs) in goldfish central nervous system. The TLPs were immunoreactive with antibodies that recognized the carboxy-terminal domain of mammalian tau, but not with antibodies that recognized the amino-terminus. The TLPs of goldfish exhibited the basic properties of tau proteins including neuronal specificity, structural heterogeneity, heat stability and the ability to co-assemble with tubulin. We propose that TLPs may represent a precursor of tau, that share the microtubule binding domain and the carboxy-terminal domain with mammalian tau proteins. In contrast the amino-terminus of the TLPs is much shorter and may represent a more variable domain of tau proteins.

[SCA1, SCA2, MJD/SCA3 (CAG)n mutation detection and analysis in patients with hereditary spinocerebellar ataxia from Chinese families]

OBJECTIVE

To assess the frequency of the SCA1, SCA2, MJD/SCA3 CAG trinucleotide repeat expansions ((CAG)n) among individuals diagnosed with hereditary spinocerebellar ataxia (SCA) from Chinese families.

METHOD

The SCA1, SCA2, MJD/SCA3 (CAG)n mutation were detected with the polymerose chain reaction (PCR), denaturing polyacrylamide gel and silver staining technique in 79 patients with autosomal dominant SCA from 50 Chinese families.

RESULTS

Among 50 kindreds, 2% (1/50) had the SCA1, (CAG)n, 6% (3/50) had the SCA2, (CAG)n, whereas 48% (24/50) were positive for the MJD/SCA3 (CAG)n. Thus, together SCA1, SCA2, and MJD/SCA3 represent 56% (28/50) of the autosomal dominant ataxias in our group. In two SCA1 patients the CAG repeat was expanded to 53-62 repeats, whereas in normal ivdividuals was 12-36 repeats. In seven SCA2 patients the CAG repeat was expanded to 43-47 repeats, whereas in normal ivdividuals was 22-30 repeats. In forty-two MJD/SCA3 patients the CAG repeat was expanded to 63-78 repeats, whereas in normal ivdividuals was 15-38 repeats. The SCA1, SCA2, MJD/SCA3 (CAG)n mutation were excluded in the other 28 SCA patients from 22 families.

CONCLUSION

The frequency of MJD/SCA3 is substantially higher than that of SCA1 and SCA2 in the autosomal dominant SCA from Chinese families. Chinese patients with MJD/SCA3 are non-Portuguese patients with MJD/SCA3. Clinical expressions of the various SCAs overlap one another, making a diagnostic classification based on phenotype inaccurate in many instances. It is important for SCA clinical study to make a SCA gene diagnosis and genomic classification.

Apolipoprotein(a) attenuates endogenous fibrinolysis in the rabbit jugular vein thrombosis model in vivo

BACKGROUND

In many case-control as well as epidemiological studies, increased lipoprotein(a) [Lp(a)] levels are considered to constitute an independent risk factor for premature coronary artery and cerebrovascular disease. Lp(a) resembles an LDL particle with an additional linked protein [apolipoprotein(a), apo(a)], whose molecular structure has been demonstrated to be homologous to the fibrinolytic proenzyme plasminogen. Because of the high similarity between plasminogen and apo(a), apo(a) may potentially interfere in the fibrinolytic system by competing with plasminogen for fibrin binding sites. In vitro studies have demonstrated that Lp(a) indeed competes with plasminogen binding to fibrin and inhibits tissue plasminogen activator (TPA)-mediated activation of plasminogen. No direct in vivo studies to test this hypothesis have been performed.

METHODS AND RESULTS

To test this hypothesis, we studied the effect of a recombinant form of apo(a) on endogenous and TPA-mediated thrombolysis in an in vivo model of experimental venous thrombosis. Thrombi containing either 16 microg r-apo(a), 8 microg r-apo(a), or vehicle (HEPES-buffered saline, control) were formed in the jugular veins of a rabbit and showed significantly reduced endogenous thrombolysis after 60 minutes in a dose-dependent fashion, ID 2.7+/-0.9% and 4.6+/-1.8%, respectively, versus 7.4+/-1.6% of that of the control. High concentrations of incorporated apo(a) significantly reduced TPA-induced thrombolysis (12.2+/-2.5% versus 22.2+/-2.6% in the control thrombi), but no effect of lower concentrations of incorporated r-apo(a) was demonstrated on the exogenous TPA-induced thrombolysis.

CONCLUSIONS

The present study demonstrates the attenuation of endogenous fibrinolysis by apo(a) in an in vivo model of experimental venous thrombosis, lending support to the proposed mechanism of impaired fibrinolysis by which Lp(a) may contribute to atherothrombotic disorders.

[An experimental study of angiogenesis inhibitor TNP-470 on tumor growth and metastasis of Lewis lung carcinoma]

OBJECTIVE

The inhibition effect of angiogenesis inhibitor TNP-470 on tumor growth and metastasis was studied using Lewis lung carcinoma.

METHODS

Lewis lung carcinoma cells(2.4 x 10(6)/mouse) were inoculated subcutaneously to 20 mice, they were randomized into 2 groups. From the 2nd day, the treated group was given 40 mg/kg of TNP-470 s.c. q.o.d. (8 times) and the control group was given vehicle only (3% ethanol). On the 22nd day, the weight of the subcutanous tumors and the lung metastasis rates of the 2 groups were detected. The results were analysed by Student-t and chi 2 test.

RESULTS

The tumor weight of the control and treated group was 3.77 +/- 1.05 g and 1.98 +/- 0.96 g, respectively (P = 0.0009). The lung metastasis rate of the control and treated group was 80%(8/10) and 30%(3/10), respectively (P = 0.03).

CONCLUSION

These results suggest that the angiogenesis inhibitor TNP-470 has a strong inhibitory effect both on growth of the primary tumor and metastasis of Lewis lung carcinoma.

Mechanism of the potentiation of vasoconstriction by neuropeptide Y in arterioles from the submucosa of the guinea-pig small intestine

1. Neuropeptide Y (NPY; 3-100 nmol/L) caused a concentration-dependent potentiation of constriction in response to noradrenaline or the thromboxane mimetic U46619 in arterioles from the submucosa of the guinea-pig small intestine. 2. In arterioles permeabilized by exposure to the alpha-toxin of Staphylococcus aureus and maintained in Ca(2+)-buffered medium, NPY potentiated the contractile effects of Ca2+. The magnitude of the potentiation was the same as in intact arterioles. 3. Exposure of arterioles to 1 mumol/L nifedipine to inhibit Ca2+ influx or to 20 mumol/L cyclopiazonic acid to abolish Ca2+ uptake into internal stores had no effect on the potentiating action of NPY.

[The effects of He-Ne laser on the revascularization of the distal part of the subdermal vascular network skin flap]

The distal part of the subdermal vascular network (SVN) random skin flap on the rabbit was radiated with He-Ne laser at an energy density of 3.15 J/cm2. The blood vessels of the flap were perfused with Chinese ink. Histological examinations and image analysis were applied to evaluate the effects of He-Ne laser radiation on the SVN skin flap. It was found that the revascularization and the survival rate of the SVN random skin flap were highly related with the proportion of the length to width of the flap in the early stage. The radiation of the He-Ne laser could improve the microcirculation of the flap and increase its survival rate, which was mainly resulted from dilation of the blood vessels, especially the veins, and anastomosis of the vessels between the flap and the recipient site.

[Isolation of band-specific (CA)n microsatellites from human chromosome 8q24.1]

Fourty eight recombinant plasmids containing CA repeats were isolated from human chromosome 8q24.1 band-specific pUC19 library. Among them, inserted DNA fragments from 12 plasmids were sequenced, and one new highly polymorphic (CA)n microsatellite was obtained (coding: D8S7F). It contained 11 alleles. The estimated heterozygosity reached 0.84 and 0.83 among Chinese Han Nationality people and American Anglo-Saxons respectively. It was assigned to chromosome 8 by using a human-rodent hybrid cell panel.

[Surgical treatment of primary epicardial tumors]

Seven cases of primary epicardial tumors of 3200 cardiac operation cases were diagnosed definitely, including benign in 5, malignant in 2. Among them, readical resection was performed in 5 cases, partial resection in 1, and decompression of pericardium in 1. Data of this series were often regarded as tuberculous pericarditis or others incorrectly. UCC, CT and MRI were helpful in diagnosis. The authors emphasize early surgical treatment as soon as possible and using the different methods of operation whether to utilize cardiopulmonary bypass or not according to site, size and characteristics of tumors to resect tumors, if necessary, reconstruction the heart wall to maintain blood follow dynamics. The prognosis of the diseases was related to the pathology and the area of invasion of tumors.

Cloning and characterization of PDK4 on 7q21.3 encoding a fourth pyruvate dehydrogenase kinase isoenzyme in human

Different isoenzymes of pyruvate dehydrogenase kinase (PDK) inhibit the mitochondrial pyruvate dehydrogenase complex by phosphorylation of the E1alpha subunit, thus contributing to the regulation of glucose metabolism. By positional cloning in the 7q21.3-q22.1 region linked with insulin resistance and non-insulin-dependent diabetes mellitus in the Pima Indians, we identified a gene encoding an additional human PDK isoform, as evidenced by its amino acid sequence identity (>65%) with other mammalian PDKs, and confirmed by biochemical analyses of the recombinant protein. We performed detailed comparative analyses of the gene, termed PDK4, in insulin-resistant and insulin-sensitive Pima Indians, and detected five DNA variants with comparable frequencies in both subject groups. Using quantitative reverse transcription polymerase chain reaction, we found that the variants identified in the promoter and 5'-untranslated region did not correlate with differences in mRNA level in skeletal muscle and adipose tissue. We conclude that alterations in PDK4 are unlikely to be the molecular basis underlying the observed linkage at 7q21.3-q22.1 in the Pima Indians. Information about the genomic organization and promoter sequences of PDK4 will be useful in studies of other members of this family of mitochondrial protein kinases that are important for the regulation of glucose metabolism.

[The new concept of the cutaneous vascular framework in the leg]

An anatomical study was carried out using 15 legs of fresh cadavers. According to skin angiography, the authors set up a new concept of the vascular structure of skin and skin flap. The characteristics of the blood supply to the skin were revealed and analyzed. The first vascular frame unit, the second vascular frame unit and the superficial fascial network were described. The willow-shaped descending vascular branches were found and discussed, and they constituted a special blood supply in subcutaneous tissue.

Regulation of the B cell response to T-dependent antigens by classical pathway complement

Mice deficient in complement components C3 (C3 -/-) and C4 (C4 -/-) were found to have a profound defect in their Ab response to a T-dependent Ag (bacteriophage (phi X174). Characterization of the deficient mice demonstrated a diminished level of peanut agglutinin+ germinal centers and a failure in isotype switching despite normal B cell signaling in vitro. The nature of the defect was found to lie at the B cell level, as the T cells were primed in C3- and C4-deficient mice as well as those in wild-type mice. These results, and the finding that the defect could be partly reversed by a 10-fold increase in Ag dose, support the hypothesis that covalent attachment of complement ligands, i.e., C3b and C3d to the Ag-Ab complex, increases its immunogenicity.

Regulation of the B cell response to T-dependent antigens by classical pathway complement

Mice deficient in complement components C3 (C3 -/-) and C4 (C4 -/-) were found to have a profound defect in their Ab response to a T-dependent Ag (bacteriophage (phi X174). Characterization of the deficient mice demonstrated a diminished level of peanut agglutinin+ germinal centers and a failure in isotype switching despite normal B cell signaling in vitro. The nature of the defect was found to lie at the B cell level, as the T cells were primed in C3- and C4-deficient mice as well as those in wild-type mice. These results, and the finding that the defect could be partly reversed by a 10-fold increase in Ag dose, support the hypothesis that covalent attachment of complement ligands, i.e., C3b and C3d to the Ag-Ab complex, increases its immunogenicity.

Ratiometric measurement of endothelial depolarization in arterioles with a potential-sensitive dye

A fluorescence ratio technique based on the voltage-sensitive dye 1-(3-sulfonatopropyl)-8-[beta-[2-di-n-butylamino)-6-naphythyl++ +]vinyl] pyridinium betaine (di-8-ANEPPS)has been developed for recording membrane potential changes during vascular responses of arterioles. Perfusion of hamster cheek pouch arterioles with the dye labeled the endothelial cell layer. voltage responses from the endothelium of intact arterioles were determined by analysis of voltage-induced shifts in fluorescence emission wavelengths from dye spectra imaged from the vessel wall. Membrane depolarization caused the dye spectrum to shift toward blue wavelengths, with maximal fluorescence changes near 560 and 620 nm. In isolated nonperfused arterioles, comparison of continuous dual-wavelength recordings with simultaneous microelectrode recordings showed that the ratio of fluorescence intensities (fluorescence at 620 nm to fluorescence at 560 nm) accurately followed changes in membrane potential (6-21 mV) during vasoconstriction. The dye response was linear with respect to potential changes from -56 to -6 mV, with a voltage sensitivity of 9.7% change in the ratio per 100 mV. Membrane potential responses from in vitro and in vivo arterioles after potassium stimulation consisted of rapid ( < 0.5 -s) depolarization followed by slow repolarization over several seconds. Potassium-induced depolarizations were conducted along arterioles, and the values of the electrical length constant for conducted depolarization determined by optical and microelectrode methods were in agreement. We conclude that ratio analysis of di-8-ANEPPS fluorescence emission can be used to accurately record membrane potential changes on the time scale of seconds during vasomotor activity from arterioles.

[Quantitative study of velopharyngeal function post-palatoplasty]

The computer of nasopharyngeal fiberscope(NPF) for quantitative analysis was carried out to assess the palate articulation of 43 subjects,and normal articulation of 60 subjects.The rest,/a/,/s/and /m/ articulation of NPF pictures were calculated for veloparyngreal function via computer.

[Diagnosis and surgical management of pancreatic pseudocysts]

Fifty-two patients with pancreatic pseudocysts were treated surgically between 1968 and 1994. Clinical symptoms were non-specific. Ten patients with acute pancreatitis were managed conservatively and resolution occurred in 3 patients. 42 patients underwent operation. Internal drainage was performed in 28 patients, external drainage in 8, others in 6. Pancreatic fistulas occurred in the external drainage group, 2 patients died and 1 patient had the of recurred pseudocyst. There were no complications in the internal drainage group. It was quite different in the external drainage group. The management should differ in that acute and chronic pancreatic pseudocysts. Patients with pseudocysts of chronic pancreatitis could undergo emergent surgery of internal drainage because waiting 6 weeks for maturation of the pseudocysts after diagnosis was unnecessary and even hazardous. However, if pseudocyst developed after acute pancreatitis, it should be watched for up to 6-8 weeks. During this period the pseudocyst perhap disappeared spontanously or matured for surgery.

Polymers with Very Low Polydispersities from Atom Transfer Radical Polymerization

A radical polymerization process that yields well-defined polymers normally obtained only through anionic polymerizations is reported. Atom transfer radical polymerizations of styrene were conducted with several solubilizing ligands for the copper(I) halides: 4,4'-di-tert-butyl, 4,4'-di-n-heptyl, and 4,4'-di-(5-nonyl)-2,2'-dipyridyl. The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities (ratio of the weight-average to number-average molecular weights of 1.04 to 1.05). Similar results were obtained for the polymerization of acrylates.

Disruption of the Cr2 locus results in a reduction in B-1a cells and in an impaired B cell response to T-dependent antigen

Covalent attachment of activated products of the third component of complement to antigen enhances its immunogenicity, but the mechanism is not clear. This effect is mediated by specific receptors, mCR1 (CD35) and mCR2 (CD21), expressed primarily on B cells and follicular dendritic cells in mice. To dissect the role of mCR1 and mCR2 in the humoral response, we have disrupted the Cr2 locus to generate mice deficient in both receptors. The deficient mice (Cr2-/-) were found to have a reduction in the CD5+ population of peritoneal B-1 cells, although their serum IgM levels were within the range of normal mice. Moreover, Cr2-/- mice had a severe defect in their humoral response to T-dependent antigens that was characterized by a reduction in serum antibody titers and in the number and size of germinal centers within splenic follicles. Reconstitution of the deficient mice with bone marrow from MHC-matched Cr2+/+ donors corrected the defect, demonstrating that the defect was due to B cells themselves. These results indicate an obligatory role of B cell complement receptors in responses of the B cells to protein antigens.

Carbon monoxide dehydrogenase from Clostridium thermoaceticum: quaternary structure, stoichiometry of its SDS-induced dissociation, and characterization of the faster-migrating form

The molecular mass (M(r)) of the nickel- and iron-sulfur-containing enzyme CO dehydrogenase from Clostridium thermoaceticum was determined by sedimentation equilibrium ultracentrifugation to be 300,000 +/- 30,000 Da. Since the enzyme is known to contain equal numbers of two types of subunits (M(r) = 82,000 Da for alpha and 73,000 Da for beta), this indicates an alpha 2 beta 2 quaternary structure. The enzyme was previously thought to have an alpha 3 beta 3 structure because it migrates through calibrated size-exclusion chromatographic columns with an apparent M(r) of about 420,000 Da. The disproportionately fast migration rate suggests that the enzyme is nonspherical. SDS induces the dissociation of an alpha subunit, yielding a stable species called FM-CODH. FM-CODH had a molecular mass of 210,000 +/- 30,000 Da, indicating an alpha 1 beta 2 structure. It contained 2.1 +/- 0.3 Ni and 16 +/- 3 Fe per alpha 1 beta 2, exhibited S-->Fe charge-transfer transitions typical of Fe-S proteins, and afforded the gav = 1.82, 1.86, and 1.94 EPR signals. Quantitation of the 1.82 and (1.94 +/- 1.86) signals afforded 0.35 and 1.9 spin/alpha 1 beta 2, respectively. FM-CODH samples exhibited CO oxidation activity, but little CO/acetyl-CoA exchange activity. Some FM-CODH samples exhibited CO oxidation activities as high as native enzyme. These results, along with the quantified spin intensities of the EPR signals, indicate that FM-CODH contains the B- and C-clusters and suggest that these clusters are located in the beta subunit. The alpha subunit that dissociated during formation of FM-CODH is not required for CO oxidation activity. FM-CODH is either devoid of A-clusters, or if such clusters are present, they have lost their ability to exhibit substantial NiFeC signals and CO/acetyl-CoA exchange activity. Incubating FM-CODH and alpha yielded a species that migrated through polyacrylamide gels at the same rate as native enzyme, and had a molecular mass indicating an alpha 2 beta 2 structure. Thus, the SDS-induced dissociation of the enzyme appears to be reversible.

Drug delivery systems: water soluble taxol 2'-poly(ethylene glycol) ester prodrugs-design and in vivo effectiveness

Water soluble 2'-taxol poly(ethylene glycol) (PEG) esters have been synthesized and shown to function in vitro as prodrugs. However, in vivo experiments clearly establish that in order for these prodrugs to behave in a predictable fashion, the molecular weight of PEG must be of such magnitude so as to maintain a t1/2(circulation) > t1/2(hydrolysis). When PEG derivatives of molecular weight approximately 40 kDa were employed with paclitaxel, ca. 4% by weight of paclitaxel was carried by the water soluble prodrug form, and equivalent in vivo toxicity and increased life expectancy in the P388-treated mouse was observed. An effective method for prescreening prodrugs was found to be the acute murine lethality, which reflects the equivalency of the solubilized transport form and the native drug.

[Investigation on VNTR in intron 40 of vWF gene in Chinese Han population]

The VNTR in the intron 40 of vWF gene was investigated with a method of combination of Amp-FLP and RFLP. Two amplified fragments from a heterozygous person were separated by a non-hydratable polyacrylamide electrolyte gradient electrophoresis. After elution from gel, the preliminary products were amplified again, the amplified fragments were digested with AluI, then the genotype could be directly determined through electrophoresis. For the first time SSCP was used to detect the subtypes of microsatellite DNA. 136 alleles were found from 156 unrelated Hans in Changsha area. There were 153 genotypes in this sample and all of them were heterozygous. The calculated heterozygosity was 0.9884. The distribution of genotypes was in according with the Hardy-Weinberg equilibrium. The polymorphic information content (PIC) was 0.9883. The polymorphism of this VNTR was the highest one in the Amp-FLPs that had been found before. Our data did not show any recombination even in 2 generations of 66 families and 3 generations of 5 families. Aco-dominant segregation was demonstrated.

Fumonisin toxicity and sphingolipid biosynthesis

Fumonisins are inhibitors of sphinganine (sphingosine) N-acyltransferase (ceramide synthase) in vitro, and exhibit competitive-type inhibition with respect to both substrates of this enzyme (sphinganine and fatty acyl-CoA). Removal of the tricarballylic acids from fumonisin B1 reduces the potency by at least 10 fold; and fumonisin A1 (which is acetylated on the amino group) is essentially inactive. Studies with diverse types of cells (hepatocytes, neurons, kidney cells, fibroblasts, macrophages, and plant cells) have established that fumonisin B1 not only blocks the biosynthesis of complex sphingolipids; but also, causes sphinganine to accumulate. Some of the sphinganine is metabolized to the 1-phosphate and degraded to hexadecanal and ethanolamine phosphate, which is incorporated into phosphatidylethanolamine. Sphinganine is also released from cells and, because it appears in blood and urine, can be used as a biomarker for exposure. The accumulation of these bioactive compounds, as well as the depletion of complex sphingolipids, may account for the toxicity, and perhaps the carcinogenicity, of fumonisins.

Electromechanical coupling and the conducted vasomotor response

Conducted vasomotor responses are viewed as one mechanism that functionally integrates the microvasculature. It is hypothesized that the conducted vasomotor response is the result of an electrical current and its passive electrotonic spread along the length of a microvessel. We tested this hypothesis in isolated, unpressurized arterioles from the hamster cheek pouch using conventional intracellular membrane potential recording techniques. The mean resting membrane potential (RMP) was -67 mV. KCl and phenylephrine (PE) pulse-stimulation applied through micropipettes could both induce transient depolarizations and vasoconstrictions at the site of stimulation (local) and at conducted (560 microns) sites. It was noted, however, that the conducted vasomotor response could not be induced until the conducted electrical response exceeded a threshold of -45 mV for a minimum amount of time. The relationship between the amplitude of constriction and the amplitude-time area of depolarization above -45 mV was the same for local and conducted KCl and for conducted PE but was significantly different from that for local PE. Nifedipine greatly reduced the local and conducted mechanical but not electrical responses. Our results indicate that the conducted vasomotor responses are the result of the generation and subsequent conduction of electrical signals along the vessel but that the corresponding mechanical response occurs only when the electrical response exceeds a threshold level.

Cellular pathways of the conducted electrical response in arterioles of hamster cheek pouch in vitro

We have previously shown that conducted vasomotor responses follow patterns that are consistent with a passive spread of electrical current along the length of the arterioles [(Xia and Duling, Am. J. Physiol. 269 (Heart Circ. Physiol. 38): H2022-H2030, 1995]. In this study, we define the cells through which the current flows. Isolated arterioles of hamster cheek pouch were used. The mean resting membrane potential (RMP) for randomly sampled arteriolar cells was -67 mV. When cell types were identified by dye injection, the RMPs were -68 and -67 mV for smooth muscle (SM) and endothelium (EC), respectively. Pulses of KCl induced transient, monophasic depolarizations at the site of stimulation (local), which were conducted decrementally along the length of the arteriole over several millimeters. During electrical conduction, three patterns of responses could be observed, but identical patterns of the conducted electrical responses were always observed in SM and EC. Phenylephrine stimulation also caused transient local and conducted depolarizations in both SM and EC. As with KCl stimuli, shapes of conducted electrical responses were identical in records made in both cell types. The results suggest that SM and EC are electrically coupled both homocellularly and heterocellularly.

[Study on the retrofascial space of the dorsum nasi and its clinical significance]

Fifty-seven adult and two children cadavers were dissected to study the position, size and structure of the retrofascial space of the dorsum nasi. The space lay between the periosteum, perichondrium and the fascia dorsum nasi. The shape of the space is like a pyramid. The space averaged 3.09 +/- 0.66 cm in length. The anatomical characteristics, individual variation and clinical significance of this space were discussed.

DNA content and morphological parameters in synovial sarcoma and synovioma

By using image analysis technique with 6 normal synovial tissue specimens as controls, nuclear DNA content and morphological parameters in specimens from 51 synovial sarcomas and 15 synovioma were examined quantitatively. The DNA content in synovial sarcoma and synovioma was significantly different (P < 0.01), and that of synovioma and normal synovial tissue was also different (P < 0.05). Morphological parameters including nuclear areas and perimeters differed significantly among the above three groups (P < 0.01). There was no correlation between the DNA content of synovial sarcoma and its histologic type (P > 0.05), but the DNA content greatly differed between its higher and lower differentiated grade in each type (P < 0.01). The DNA content in synovial sarcoma IIA stage, according to Enneking's staging system was lower than that in IIB, IIIA and IIIB (P < 0.05). The 5-year survival rate of synovial sarcoma with diploid/nearly diploid (D/ND) pattern was higher than that of aneuploid (AN) pattern (P = 0.028). The study suggests that analysis of the DNA content and morphological parameters of tumor cells is helpful in the diagnosis and pathologic grading of synovial sarcoma. It also provides a guide to clinical operation and estimation of the prognosis. Although synovioma is usually a well-differentiated and benign lesion, this investigation also suggested that increased DNA content may be an indication of poor prognosis for this neoplasm.

Poly(ethylene glycol) fluorescent linkers

The first examples of PEG linkers containing the highly fluorescent dansyl group have been synthesized. Quantum yields of these PEG fluorescent linkers (PFL) were determined and utilized in calculating the PEG number of various protein conjugates. The method was also shown to be applicable to lower molecular weight drugs as exemplified by taxol.

[Processing of pyritum from different sources]

Studies on the processing of Pyritum from different source were conducted by means of indentical technological procedure using total sulphur, S,FeS2 and Fe7S8 as indexes. The results showed considerable differences in compositions of the processed products.

Excessive insulin receptor serine phosphorylation in cultured fibroblasts and in skeletal muscle. A potential mechanism for insulin resistance in the polycystic ovary syndrome

We investigated the cellular mechanisms of the unique disorder of insulin action found in the polycystic ovary syndrome (PCOS). Approximately 50% of PCOS women (PCOS-Ser) had a significant increase in insulin-independent beta-subunit [32P]phosphate incorporation (3.7-fold, P < 0.05 vs other groups) in skin fibroblast insulin receptors that was present in serine residues while insulin-induced tyrosine phosphorylation was decreased (both P < 0.05 vs other groups). PCOS skeletal muscle insulin receptors had the same abnormal phosphorylation pattern. The remaining PCOS women (PCOS-n1) had basal and insulin-stimulated receptor autophosphorylation similar to control. Phosphorylation of the artificial substrate poly GLU4:TYR1 by the PCOS-Ser insulin receptors was significantly decreased (P < 0.05) compared to control and PCOS-n1 receptors. The factor responsible for excessive serine phosphorylation appeared to be extrinsic to the receptor since no insulin receptor gene mutations were identified, immunoprecipitation before autophosphorylation corrected the phosphorylation defect and control insulin receptors mixed with lectin eluates from affected PCOS fibroblasts displayed increased serine phosphorylation. Our findings suggest that increased insulin receptor serine phosphorylation decreases its protein tyrosine kinase activity and is one mechanism for the post-binding defect in insulin action characteristic of PCOS.

Decomposition of carbon monoxide dehydrogenase into alpha metallosubunits and a catalytically-active form consisting primarily of beta metallosubunits

Carbon monoxide dehydrogenase from Clostridium thermoaceticum, with an alpha 3 beta 3 quaternary structure, was incubated with dithiothreitol and 740-78,000 equiv/alpha 3 beta 3 of sodium dodecyl sulfate (SDS), followed by electrophoresis under anaerobic native conditions. Three catalytically-active bands and four inactive bands were obtained, in proportions dependent on the amount of SDS added. The catalytically-active bands, called SM-CODH, NM-CODH, and FM-CODH, migrated slower than, similar to, and faster than native enzyme, respectively. Two-dimensional electrophoresis revealed that SM-CODH and NM-CODH contained approximately equal proportions of the alpha and beta subunits, while the beta/alpha ratio for FM-CODH was about 2.7. The four inactive bands were identified as the beta subunit, two forms of the alpha subunit (called alpha and alpha'), and a form that migrated similarly to native enzyme. Overloaded gels revealed that alpha and each active band had brown color, indicating intact Fe-S clusters in these species. Higher concentrations of SDS (> 1600 equiv/alpha 3 beta 3) and/or incubation at temperatures > 15 degrees C yielded more alpha and beta subunits at the expense of the catalytically-active bands. When incubated at 70 degrees C in 78,000 equiv/alpha 3 beta 3 of SDS, alpha quantitatively converted to alpha', suggesting that alpha' is a denatured form. FM-CODH appears to be an intermediate in the decomposition of CODH by SDS and to have either an alpha 1 beta 3 or alpha 1 beta 2 quaternary structure.(ABSTRACT TRUNCATED AT 250 WORDS)

[Cytogenetic analysis of four cases of hermaphroditism]

On the basis of cytogenetics karyotype analysis, southern blot hybridization using sex-determining region of the Y chromosome (SRY) probe and amplified cation of the genomic DNA between the SRY code region by specific primers through polymerase chain reaction (PCR) have been performed in four cases of hermaphroditism. The results showed that, in 1 46, XY female and 1 45, XO/46, XY female, the SRY specific hybridization band and PCR amplified band could not be detected; in 1 46, XX male, the specific hybridization and PCR band showed SRY gene as in normal male; in another true hermaphrodite, the karyotype is 46, XX/47,XXY, PCR band is detectable but not hybridization band. The mechanism of the abnormal sex differentiation of the cases was analyzed and the two detection methods were compared.

Dye tracers define differential endothelial and smooth muscle coupling patterns within the arteriolar wall

Dye tracers were chosen, based on net charge, chemical structure, and reactive groups, to test for the existence of and to provide novel insight into channel selectivities of junctional pathways connecting smooth muscle and endothelial cells of the arteriolar wall. Dyes were injected into individual smooth muscle or endothelial cells of hamster cheek pouch arterioles using microiontophoresis. Coupling, independent of tracer net charge, was seen both within and between cell layers. Endothelial cells were well coupled by all of the tested dyes. Smooth muscle junctions appeared less effective in dye transfer than endothelial junctions. Lucifer yellow was confirmed to be a poor tracer of smooth muscle gap junctions, and remarkably this dye and other related sulfate-containing molecules interfered with dye movement through smooth muscle but not endothelial junctions. Myoendothelial junctions showed a striking polarity of dye movement, with dye transfer from endothelial to smooth muscle cells but little or no transfer in the reverse direction. Because the dyes have size and charge characteristics similar to those of known cellular second messengers, these findings have important implications for cell-cell signaling in the vessel wall.

Structural characterization of an Ascaris myoglobin

Globin was purified from the body wall of adults of the parasitic nematode Ascaris suum. Internal peptide fragments were sequenced and cDNAs encoding a polypeptide of 154 amino acids isolated by polymerase chain reaction. The polypeptide lacks a signal sequence, identifying it as a cytosolic myoglobin-like species. The native protein is a dimer. The predicted amino acid sequence shares several unusual substitutions with other nematode globins. Like the abundant pseudocoelomic A. suum hemoglobin it has a Tyr at B10 and a Gln at E7, substitutions thought to be determinants of high affinity. However, the 10-fold lower oxygen affinity of body wall globin suggests that in this molecule Tyr(B10) does not form an additional hydrogen bond with the heme bound oxygen. Evolutionary analysis of the nematode globins suggests that the monodomain myoglobin-like molecules and the two-domain hemoglobin-like molecules diverged about 500 million years ago, well before the divergence of the ascarid genera Ascaris and Pseudoterranova. The absence of introns in the A. suum myoglobin, in contrast to other nematode globin genes, is consistent with the hypothesis that during evolution intron elimination was the predominant event.

Absence of insulin receptor gene mutations in three insulin-resistant women with the polycystic ovary syndrome

Women with polycystic ovary syndrome (PCOS) are markedly insulin-resistant, but the molecular mechanisms of these changes and their relationship to the hyperandrogenic state remain to be clarified. Mutations have recently been identified in the insulin receptor gene of patients with extreme forms of insulin resistance associated with hyperandrogenism (eg, type A insulin resistance), and these mutations account for the insulin resistance in such patients. We performed this study to determine whether mutations in the coding portion of the insulin receptor gene were responsible for insulin resistance in PCOS. Insulin binding studies using cultured skin fibroblasts of three obese (body mass index > 27 kg/m2) women with PCOS (ie, mild hyperandrogenemia and chronic anovulation of unknown etiology) and documented insulin resistance showed no apparent abnormalities in either the number or affinity of insulin binding sites. Direct sequencing of all 22 exons of the insulin receptor gene from two of the women with PCOS did not reveal any mutations. Furthermore, both alleles of the gene were expressed at equal levels. In a third insulin-resistant PCOS woman, there was no evidence for a mutation in the coding portion of the insulin receptor gene as determined by denaturing gradient gel electrophoresis (DGGE). We conclude that the insulin resistance in these PCOS women was caused by a defect extrinsic to the insulin receptor.