Differentially Expressed Circulating Long-Noncoding RNAS in Premature Infants with Respiratory Distress Syndrome

Purpose

Recent studies have addressed the association between lung development and long-noncoding RNAs (lncRNAs). But few studies have investigated the role of lncRNAs in neonatal respiratory distress syndrome (RDS). Thus, this study aimed to compare the expression profile of circulating lncRNAs between RDS infants and controls.

Methods

10 RDS infants and 5 controls were enrolled. RDS patients were further divided into mild and severe RDS subgroups. Blood samples were collected for the lncRNA expression profile. Subsequently, differentially expressed lncRNAs were screened out. Bioinformatics analysis was applied to establish a co-expression network of differential lncRNAs and mRNAs, and predict the underlying biological functions.

Results

A total of 135 differentially expressed lncRNAs were identified, including 108 upregulated and 27 downregulated lncRNAs (fold-change>2 and P<0.05) among the three groups (non-RDS, mild RDS and severe RDS groups). Of these lncRNAs, four were selected as showing higher fold changes and validated by qRT-PCR. ENST00000470527.1, ENST00000504497.1, ENST00000417781.5, and ENST00000440408.5 were increased not only in the plasma of total RDS patients but also in the severe RDS subgroup. Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analyses showed that differentially expressed lncRNAs may play important roles in RDS through regulating PI3KAkt, RAS, MAPK, and TGF-β signaling pathways.

Conclusion

The present results found that ENST00000470527.1, ENST00000504497.1, ENST00000417781.5, and ENST00000440408.5 may be invol ved in RDS. This could provide new insight into research of the potential pathophysiological mechanisms of preterm RDS.

[Folic acid supplementation before and during pregnancy and the risk of preeclampsia]

Objective: To investigate the relationship between folic acid supplementation and the risk of preeclampsia (PE). Methods: A total of 9 048 pregnant women were selected from the First Hospital of Shanxi Medical University in Taiyuan from March 2012 to September 2016. Among them, 882 pregnant women with PE were divided into case group, and 8 166 pregnant women without PE were divided into control group. Information on demographic characteristics, folic acid supplementation, maternal complications, and other factors were collected by face-to-face interviews after child birth in the hospital. Unconditional logistic regression analyses were used to investigate the relationship between folic acid supplementation and the risk of PE and the effects of pre-pregnancy BMI on the relationship of folic acid supplementation with the risk of PE. Results: Compared with nonusers, folic acid supplement users had reduced risk of PE (OR=0.79, 95%CI: 0.64-0.96). Folic acid supplementation before and during pregnancy were negatively related with the risk of PE (OR=0.63, 95%CI: 0.49-0.81). Pregnant women who used folic acid tablets only or used both folic acid tablets and multivitamin containing folic acid had reduced risk of PE (OR=0.81, 95%CI: 0.66-0.99; OR=0.64, 95%CI: 0.49-0.85). No significant relationship was observed in the multivitamin group. Supplemental folic acid doses of <400, 400, and >400 μg/d were related with reduced risk of PE (OR=0.62, 95%CI: 0.42-0.91; OR=0.81, 95%CI: 0.66-0.99; OR=0.68, 95%CI: 0.49-0.94). After stratified by pre-pregnancy BMI, pregnant women who used folic acid supplementation, those with pre-pregnancy BMI<24.0 kg/m(2) had reduced risk of PE (OR=0.75, 95%CI: 0.59-0.96). However, no significant relationship was observed in women with pre-pregnancy BMI≥24.0 kg/m(2). Conclusions: Folic acid supplementation before and during pregnancy were related with reduced risk of PE. Pre-pregnancy BMI might affect the relationship between folic acid supplementation and the risk of PE. Appropriate folic acid supplementation should be recommend for women with different pre-pregnancy BMI.

MicroRNA-203 inhibits invasion and induces apoptosis of laryngeal cancer cells via targeting LASP1

OBJECTIVE

To explore the role of microRNA-203 in laryngeal cancer and its underlying mechanism in regulating cell invasion and apoptosis.

PATIENTS AND METHODS

MicroRNA-203 expression in laryngeal cancer tissues and paracancerous tissues was detected by quantitative real time-polymerase chain reaction (qRT-PCR). The regulatory effects of microRNA-203 on the invasion and apoptosis of laryngeal cancer cells were detected by transwell assay and flow cytometry, respectively. Dual-Luciferase reporter gene assay was performed to access the binding condition of microRNA-203 and LASP1. Both mRNA and protein levels of LASP1 in laryngeal cancer cells were detected after transfection with microRNA-203 mimic or microRNA-203 inhibitor by qRT-PCR and Western blot, respectively. Rescue experiments were finally performed to detect whether microRNA-203 regulates laryngeal cancer development via targeting LASP1.

RESULTS

MicroRNA-203 was lowly expressed in laryngeal cancer tissues and cell lines. MicroRNA-203 knockdown in Hep-2 cells can promote the invasion and inhibit the apoptosis of laryngeal cancer cells. Subsequently, LASP1 was predicted to be the target gene of microRNA-203, which was further verified by the Dual-Luciferase reporter gene assay. LASP1 expression was negatively regulated by microRNA-203. Furthermore, rescue experiments showed that the regulatory effects of microRNA-203 on the invasion and apoptosis of laryngeal cancer cells were reversed by LASP1.

CONCLUSIONS

We showed that lowly expressed microRNA-203 could promote the invasion and inhibit apoptosis of laryngeal cancer cells via inhibiting LASP1.

[Association between maternal dietary intake and the incidence of babies with small for gestational age]

Objective: To investigate the relations between dietary intake during pregnancy and the incidence of their babies with small for gestational age (SGA). Methods: Data on demographics, dietary intake of protein, fat, and carbohydrates of the pregnant mothers during the first, second and third trimester, were collected. Information related to birth weight and gestational age of the infants were also gathered. A total of 8 102 women, who delivered their babies at the First Affiliated Hospital of Shanxi Medical University from March 2012 to September 2016, were enrolled in this project. Among them, 961 mothers had infants with SGA but the other 7 141 of them having normal infants. Unconditional logistic regression model was used to analyze the effect of dietary nutrient intake on SGA the first, second and third trimester. Results: We found that low dietary intake of protein during the first trimester and following trimesters during pregnancy were positively associated with higher risk of SGA (OR=1.534, 95%CI: 1.217-1.934; OR=1.268, 95%CI: 1.005-1.599; OR=1.310, 95%CI: 1.036-1.655). When adjusting for maternal pre-pregnancy BMI, we found that when mothers were with a pre-pregnancy BMI less than 18.5 or with low maternal intake of protein during the first trimester, positive association with higher risk of SGA (OR=1.872, 95%CI: 1.033-3.395; OR=1.754, 95%CI: 1.125-2.734), was noticed. However, for mothers with a pre-pregnancy BMI between 18.5 and 24.0 or with low protein intake during the first trimester, significant association with higher risk of SGA (OR=1.465, 95%CI: 1.089-1.972) was found. Conclusions: Through our observation, maternal dietary intake during pregnancy seemed to be associated with the risk of SGA but the effects of dietary intake were different, according to the BMI of pre-pregnancy population. Early pregnancy appeares as the key period for dietary intake which may influence the SGA.

[Study on the effects of microRNA-203 on the invasion and apoptosis of laryngeal cancer cells via targeting LASP1]

Objective: To explore the role of microRNA-203 in laryngeal cancer and its underlying mechanism and clarify the relationship between microRNA-203 and LASP1.Method: microRNA-203 expression in laryngeal cancer tissues and paracancerous tissues was detected by quantitative real time-polymerase chain reaction（qRT-PCR）. The regulatory effects of microRNA-203 on invasion and apoptosis of laryngeal cancer cells were detected by Transwell assay and flow cytometry, respectively. Dual-luciferase reporter gene assay was performed to access the binding condition of microRNA-203 and LASP1. Both mRNA and protein levels of LASP1 in laryngeal cancer cells were detected after transfection with microRNA-203 mimic or microRNA-203 inhibitor by qRT-PCR and Western blot. Rescue experiments were finally performed to detect whether microRNA-203 regulates laryngeal cancer development via targeting LASP1. Result: microRNA-203 was lowly expressed in laryngeal cancer tissues and cell lines.Knockdown of microRNA-203 in Hep-2 cells can promote the invasiveness and inhibit apoptosis of laryngeal cancer cells. Subsequently,LASP1 was predicted to be the target gene of microRNA-203，which was further verified by dual-luciferase reporter gene assay.LASP1 expression was negatively regulated by microRNA-203. Furthermore，rescue experiments showed that microRNA-203 regulates invasion and apoptosis of laryngeal cancer cells via targeting LASP1. Conclusion： Low expression of microRNA-203 could promote the invasion and inhibit apoptosis of laryngeal cancer cells viainhibiting LASP1. microRNA-203 and LASP1 both play a very important role in the development of laryngeal cancer..

[The study about the role of laryngopharyngeal reflux for the hemorrhage after tonsillectomy]

Objective:To assess the role of LPR in the development of complications, such as hemorrhage, following tonsillectomy in adult patients. We want to provide a guidence for future clinical practice.Method:Totally 70 adult patients who had indication of tonsillectomy were recruited and divided into two groups, the laryngopharyngeal reflux (LPR) group and the control group, which were identified by the results of Reflux Symptom Index (RSI) and Reflux Finding Score (RFS). We observed and compared the postoperative complications of the two groups and analyzed the role of LPR.Result:All the patients complained pain after surgery. The duration of the pain in LPR group was much longer than that of control group. The mean body temperature in both groups was not significantly different (P＞0.05). There were six cases of bleeding in the LPR group, while only one case of bleeding occurred in the control group. The difference was statistically significant (P<0.05). There were no cases of infection or pulmonary complications in both groups. All patients were discharged successfully.Conclusion:LPR is closely related to the complications following tonsillectomy.

[Relationship of preoperative coronal intervertebral angle changes in the lumbosacral region with postoperative trunk shift after congenital scoliosis surgery]

OBJECTIVES

To investigate the relationship between the preoperative coronal intervertebral angle changes and postoperative trunk shift (TS) in patients who received congenital scoliosis correction.

METHODS

The data of 921 patients with congenital scoliosis, who received posterior congenital scoliosis correction and internal fixation, was retrospectively analyzed. Anteroposterior (AP) whole spine standing radiographs and right and left lateral bending radiographs were taken preoperatively, and AP whole spine standing radiographs were obtained postoperatively and at the final follow-up. TS was measured in the coronal plane, and intervertebral angle change was the sum of the absolute values of L4-S1 intervertebral angle changes in the coronal plane, and was determined before surgery, postoperatively, and at final follow-up.

RESULTS

A total of 38 patients with a mean age of 16.42±8.36 years old and a mean follow-up of 12.4 months (range, 6 to 36 months) were included. A median negative correlation were found between TS at the final follow-up and total variance of bending (r=-0.51, P=0.001). Groups were defined by two methods: coronal intervertebral angle changes ≥10° or <10°, and final follow-up TS < 20 mm or ≥ 20 mm. TS at the final follow-up was significantly greater in the <10° group than the ≥10° group (32.45 vs 12.44 mm, P=0.001), and coronal intervertebral angle changes was significantly greater in the TS < 20 mm group than the ≥ 20 mm group (14.2° vs 6°, P=0.001).

CONCLUSION

Postoperative TS which will not compensate spontaneously can be predicted by measurement of the preoperative intervertebral interspace angle in the congenital scoliosis lumbosacral region.

Relation between self-image score of SRS-22 with deformity measures in female adolescent idiopathic scoliosis patients

BACKGROUND

Adolescent idiopathic scoliosis (AIS) is a pathology which affects the individual's functioning in the widely understood physical, psychic, and social aspects. More attention should be paid to patients' perception of self-image when evaluating the spine deformity. The present retrospective study evaluated the associations between the deformity measures and self-image score as determined by the SRS-22 questionnaire in Chinese female AIS patients.

HYPOTHESIS

The self-image score correlates significantly with deformity measures. The location of main curve apex and the number of curve could affect the self-image score.

MATERIALS AND METHODS

We retrospectively reviewed the records of 202 female patients, collected data on patient's age, body mass index, radiographic and physical measures and self-image score of SRS-22 questionnaire. According to the location of main curve apex and the number of curve, the patients were divided to different subgroups. Correlations between deformity measures and self-image score of different groups were evaluated by the Spearman correlation test.

RESULTS

The self-image score correlated negatively with the main Cobb angle, apical vertebral translation (AVT), and razor hump height. There is no significant difference of self-image score between thoracic curve (TC) and thoracolumbar curve (TL/LC) subgroups. And the self-image scores of one-curve, two-curve and three-curve subgroups are similar.

DISCUSSION

For Chinese female AIS patients in our study, self-image was found to correlate negatively with the main Cobb angle, AVT and razor hump height. And the location of scoliosis apex and the number of curve are not influencing factors of self-image perception.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Roles of nicotinic acetylcholine receptors in stem cell survival/apoptosis, proliferation and differentiation

The potential of stem cells in regenerative medicine, developmental biology, and drug discovery has been well documented. For example, stem cells have the extraordinary ability of self-renewal, and also give rise to many specialized cells. It is clear that stem cell technology has revolutionized our understanding of modern biology and medicine and provided new insights into the mechanisms controlling basic cell biology and various diseases. Nicotinic acetylcholine receptors (nAChRs) are prototypical members of the ligand-gated ion channel super family of neurotransmitter receptors that play many critical roles in brain and body function. It has been demonstrated that in addition to mediation of classical excitatory neurotransmission at some loci and modulation of release of neurotransmitters in some cases, nAChRs also play important roles in influencing synaptic architecture and plasticity as well as neuronal survival/death. Recently, emerging lines of evidence have suggested that nAChRs express on stem cells, where they likely mediate crucial effects of cholinergic signaling on stem cell survival/apoptosis, proliferation, differentiation and maturation. In this review, we summarize current development in cholinergic modulations of stem cell survival/apoptosis, proliferation and differentiation in order to evaluate the impact of nAChRs in stem cell biology and pathology.

Vertebroplasty by use of a strontium-containing bioactive bone cement

STUDY DESIGN

A review of the laboratory and clinical data for a new strontium-containing hydroxyapatite bioactive bone cement.

OBJECTIVES

To compare the properties of the strontium-containing bioactive bone cement with those of polymethyl methacrylate (PMMA) and hydroxyapatite (HA) bone cements.

SUMMARY OF BACKGROUND DATA

Vertebroplasty and kyphoplasty using conventional PMMA bone cements have been effectively used to treat osteoporotic spine fractures with good short- and medium-term results. However, PMMA has some undesirable properties, including its high setting temperature, lack of osseointegration, and large stiffness mismatch with osteoporotic bone. These properties are responsible for some postoperative complications.

METHODS

Strontium-containing hydroxyapatite (Sr-HA) bioactive bone cement consists of a filler blend of strontium-containing hydroxyapatite, fumed silica and benzoyl peroxide; and a resin blend of bisphenol A diglycidylether methacrylate, triethylene glycol dimethacrylate, poly(ethylene glycol) methacrylate, and N, N-dimethyl-p-toluidine. Its properties, including mechanical strength, setting temperature, biocompatibility, and osseoinduction, were compared with other cements in vitro and in vivo. Early clinical results are presented.

RESULTS

The Sr-HA cement has a setting time of 15 to 18 minutes, a maximum setting temperature of 58 degrees C, a compressive strength of 40.9 MPa, bending strength of 31.3 MPa, and a bending modulus of 1,408 MPa. The bending strength and modulus are closer to human cancellous bone. Sr-HA cement promotes osteoblast attachment and mineralization in vitro and bone growth and osseointegration in vivo. In a pilot study, 23 cases of osteoporotic fractures treated with this cement with a mean follow-up of 18 months suggest that it is as effective as PMMA in relieving pain.

DISCUSSIONS

Oral strontium has been shown to induce new bone formation and is effective in reducing fracture risk in osteoporosis. Our data suggest that strontium delivered locally has the same effect; thus, the combination of strontium with HA in a cement with a low setting temperature, adequate stiffness, and low viscosity makes this a good bioactive cement for vertebroplasty and kyphoplasty.

Microfracture and changes in energy absorption to fracture of young vertebral cancellous bone following physiological fatigue loading

STUDY DESIGN

Fifty-five human thoracolumbar vertebrae were randomly fatigue loaded and analyzed.

OBJECTIVES

The purpose of this study was to explore the relationship between fatigue loading, trabecular microfracture, and energy absorption to fracture in human cadaveric thoracolumbar vertebrae.

BACKGROUND

Although trabecular microfractures are found in vivo and have been produced by fatigue loading in vitro, the effect of the level of physiologic fatigue loading on microfracture and energy absorption has not been investigated.

METHODS

Fifty-five human thoracolumbar vertebrae (T11-L4) were randomly divided into 5 groups: 1) control (no loading, n = 6); 2) axial compression to yield (n = 7); and 3-5) 20,000 cycles of fatigue loading at 2 Hz (each n = 14). The level of fatigue loading was determined as a proportion of the yield load of Group 2 as follows: 10% (Group 3), 20% (Group 4), and 30% (Group 5). Half of the specimens in groups 3 to 5 were used for radiographic and histomorphometric analysis to determine microfracture density and distribution, whereas the other half were tested to determine the energy absorption to yield failure.

RESULTS

No radiographic evidence of gross fracture was found in any of the groups following fatigue loading. A mean 7.5% increase in stiffness was found in specimens subject to cyclic loading at 10% of yield stress (Group 3). Fatigue at 20% (Group 4) and 30% of yield stress (Group 5) caused significantly higher (P < 0.05) increases in mean stiffness of 23.6% and 24.2%, respectively. Microfracture density increased from 0.46/mm in Group 3 to 0.66/mm in Group 4 and 0.94/mm in Group 5 (P < 0.05). The energy absorbed to failure decreased from 21.9 J in Group 3 to 18.1 J and 19.6 J in Groups 4 and 5, respectively (P < 0.05).

CONCLUSIONS

Fatigue loading at physiologic levels produced microfractures that are not detectable by radiography. Increased fatigue load results in an increase in microfracture density and decrease energy absorbed to fracture, indicating a reduced resistance to further fatigue loading.

[Application of diapason instrumentation for treatment of unstable lumbosacral spinal stenosis]

OBJECTIVE

To observe the preliminary clinical outcome of using a new instrumentation Diapason system and to introduce the characterization and surgical technique of this new system for treatment of unstable lumbar spinal stenosis.

METHODS

16 patients with unstable spinal stenosis who were treated by decompression, posterolateral intertransverse arthrodesis and transpedicle instrumentation of Diapason system, were analyzed retrospectively.

RESULTS

Lower back pain (LBP) of 16 patients were significantly alleviated after surgery (scores of LBP before operation: 47.5 +/- 0.8; scores of LBP after operation: 31.9 +/- 2.3, P < 0.001). There was no implant failure, no early or later infection and no neurological complications in 16 patients at an average of 6.2-month follow-ups. No pseudoarthrosis was observed on roentgenography.

CONCLUSION

Our short-term follow-up and limited cases study showed satisfactory preliminary result of treating unstable lumbar spinal stenosis with Diapason internal fixation.

Speech evaluation of partially implantable piezoelectric middle ear implants in vivo

OBJECTIVE

Cochlear microphonic responses (CMs) were measured in a rabbit model in the intact ear (CM1) and in ears with a partially implantable piezoelectric middle ear implant (P-MEI) (CM2) to investigate the characteristics of speech transmission of the P-MEI in vivo.

DESIGN

The spectra of pure tones, voices, and elicited CM1 and CM2 obtained from the round window before and after the implantation of a P-MEI device were calculated by using fast Fourier transform. Frequency response functions of CM1 and CM2 were used to demonstrate the functional similarity between the implanted P-MEI and the normal ossicular chain. The coherence functions between the voices and CM1 and between CM1 and CM2 were evaluated to characterize speech transmission of the P-MEI in vivo. Ten rabbit ears were used in this study. Pure tones, six Chinese vowels, and six Chinese characters were the acoustic stimuli. The CMs elicited by a list of bisyllabic words were tape-recorded and then recognized by subjects with normal hearing.

RESULTS

Using pure tones at the same intensity of 90 dB SPL, frequency response functions of the CMs between the two states (the intact ear with normal hearing and ears with a P-MEI device at the medium volume) were calculated showing great resemblance in shape. Compared with that at 1 kHz, gain factors were 10 and 20 dB, respectively, at higher frequencies. The correlation and spectral analyses of the vocalizations, CM1 and CM2, demonstrated that the harmonics of CM1 were approximately identical as those of the voices between 0.5 and 5.0 kHz with coherence functions of about 0.7 to approximately 1 at the formants' frequencies, whereas the harmonics of CM2 between 0.5 and 2.5 kHz were enhanced with the coherences near to unity at the formants' frequencies, and others <0.5 kHz and >2.5 kHz were attenuated. The recognition score of the CMs elicited by a list of bisyllabic words was >90% using subjects with normal hearing.

CONCLUSIONS

Data from this study suggest that cochlear microphonic potentials can be used as an important tool to evaluate objectively whether the implantation of a P-MEI device is successful and whether the quality in speech transmission of the P-MEI is satisfactory. Thus, the method would be of significance to clinically ascertain the performance of the device in vivo.

Neural representation of sound duration in the inferior colliculus of the mouse

In this study we examined the neuronal responses of single units to different sound durations in the inferior colliculus (IC) of the mouse. One hundred and one recorded units were classified into onset (58%), sustained (9%) on-sustained (22%), pauser (9%) and chopper (2%) response patterns. Thirty-four percent of the recorded units showing stronger responses to long stimulus durations were defined as long-duration-selective neurons. Twenty-five percent of the units preferred a narrow range of sound durations and were classified as band-pass neurons. Ten percent of the units responded preferentially to short stimulus durations and thus displayed short-duration selectivity. Twelve percent of the units that responded with nearly constant spike counts to stimuli of varying duration were classified as all-pass neurons. In contrast to the result of no short-duration-selective neurons found in chinchilla IC, we observed that some of the onset units in the IC of the mouse displayed a short duration preference. The best duration range of the duration-selective neurons in the present study corresponds to the duration range of mouse calls. We suggest that an inhibitory mechanism contributes to the duration selectivity observed in the present study.

Evidence for columnar organization in the auditory cortex of the mouse

Single cortical auditory neurons sequentially isolated within orthogonal electrode penetrations in the mouse were studied using tonal stimulation. They had common functional properties, such as firing pattern, best frequency, minimum threshold, sharpness of frequency tuning and onset latency. The finding suggests that there is columnar organization in the cortex.

[A quantitative study on the synaptic ultrastructural alterations in visual cortex in the maintenance of LTP]

The ultrastructure of synapses three hours after formation of long-term potentiation (LTP) was examined in the local microslices of visual cortical brain slices of 18-20 d rats. Slices without potentiating stimulation which were similarly incubated served as controls. The following structural changes were examined using a graph analyzer: (1) synaptic cleft width; (2) thickness of the postsynaptic densities(PSD); (3) length of the active zones; and (4) curvature of the synaptic interface. The number of synapses of different types in layer II/III of visual cortex was quantified by double-blind scoring procedures. The various counts were converted to the number of synapses per unit volume using stereological quantitation method. Analysis of variance was used for statistical evaluation. Our results suggest that field potentials reached their peak values at about one and a half hours after tetanus and could be maintained as long as three hours without decay. In comparison with the control groups, synaptic cleft width, thickness of PSD, surface density per unit volume(Sv) of the active zones, curvature of the synaptic interface, numeric density per unit volume (Nv) of all synapses, spine synapses and the Nv of perforated synapses were all increased significantly. These data suggest that the increase of Sv of active zones and the increase of the curvature of synaptic interface may be the morphological feature characterizing the maintenance of LTP, in addition to the formation of perforated synapses.

Cytoarchitecture and sound activated responses in the auditory cortex of the big brown bat, Eptesicus fuscus

Under free field and closed-system stimulation conditions, we studied the frequency threshold curves, auditory spatial sensitivity and binaurality of neurons in the primary auditory cortex (AC) of the big brown bat, Eptesicus fuscus. All 298 recorded AC neurons discharged phasically. They were recorded at depths less than 1,000 microns with response latencies of 7-25 ms, best frequencies (BFs) of 28-97 kHz and minimum thresholds (MTs) of 8-90 dB SPL. They received excitatory inputs from the contralateral ear and either excitatory (EE) or inhibitory (EI) inputs from the ipsilateral ear. These cortical neurons were tonotopically organized along the anteroposterior axis of the AC. High best frequency neurons were located anteriorly and low best frequency neurons posteriorly. They were most sensitive to sounds delivered from a restricted region of the contralateral frontal auditory space (0 degree-50 degrees in azimuth and 2 degrees up, 15 degrees down in elevation). Frontal auditory space representation appears to be systematically arranged according to the tonotopic axis such that the lateral space is represented posteriorly and the middle space anteriorly. Cortical neurons sequentially isolated from an orthogonally penetrated electrode had similar frequency threshold curves, BFs, MTs, points of maximal auditory spatial sensitivity and binaurality. The EE and EI columns are organized concentrically such that the small number of centrally located EE columns were surrounded by an overwhelming number of EI columns. Using Nissl and Golgi stains as well as c-fos immunocytochemistry, we studied the cytoarchitecture, cell types and sound elicited Fos-like immunoreactivity in the primary AC of this bat species. The primary AC of this bat species can be described into molecular (137 microns), external granular (55 microns), external pyramidal (95 microns), internal granular (102 microns), internal pyramidal (191 microns) and multiform (120 microns) layers. The main type of cells distributed among these six layers are the small, medium and large pyramidal cells. Others include the stellate, horizontal, granular, fusiform, basket, and Martinotii cells. When stimulated with 30 kHz and 79 dB SPL sounds under natural conditions, bilaterally and symmetrically distributed Fos-like immunoreactive neurons were observed in about 20% of neurons in each AC. When stimulated under monaurally plugged conditions, 39-48% more of Fos-like immunoreactive neurons were observed in the ipsilateral AC. This finding supports the fact that the primary AC receives auditory inputs mainly from the contralateral ear.

Binaural and frequency representation in the primary auditory cortex of the big brown bat, Eptesicus fuscus

This study examines the binaural and frequency representation in the primary auditory cortex (AC) of the big brown bat, Eptesicus fuscus, by using an ear-phone stimulation system. All 306 cortical neurons studied were excited by contralateral sound stimulation but they were either excited, inhibited or not affected by ipsilateral sound stimulation. These cortical neurons were columnarly organized according to their binaural and frequency-tuning properties. The excitation-excitation columns which occupy about 15% of the AC are mainly aggregated within an oval-shaped area of the central AC. The excitation-inhibition neurons and binaural neurons with mixed properties are distributed in the remaining 85% of the surrounding primary AC. Although the best frequency (BF) of these neurons shows a tendency to decrease from high to low along the anteroposterior axis of the primary AC, systematic variation in BF is not always consistent across the entire mapping area. In particular, BFs of cortical neurons isolated in the anterior AC vary quite unsystematically such that neurons with similar BFs are aggregated in isolated patches. Isofrequency and binaural columns are segregated into bands that intersect each other.

Use of infrared multiphoton photodissociation with SWIFT for electrospray ionization and laser desorption applications in a quadrupole ion trap mass spectrometer

Infrared multiphoton photodissociation (IRMPD) is combined with stored wave form inverse Fourier transforms (SWIFT) to effect dissociation and ion ejection in a quadrupole ion trap mass spectrometer. The application of IRMPD to the structural characterization of biochemical ions generated by chemical ionization and electrospray ionization and the feasibility of utilizing infrared photons for the activation of laser-desorbed metal ion-crown ether complexes was examined. The effect of helium pressure on the dissociation efficiency and relative dissociation rate constants for systems with well-known thermochemistry was evaluated. The helium pressure is not detrimental to the IRMPD experiment when nominal pressures lower than 2 x 10(-5) Torr are used. At pressures close to nominally 8 x 10(-5) Torr of helium, collisonal deactivation dominates. Results show conventional CAD is a more selective dissociation technique; however, the amount of fragment ion information generated depends highly on the qz value. IRMPD, on the other hand, is independent of the value of qz such that low rf storage values can be utilized during the irradiation period. Thus, under these conditions, informative lower mass fragment ions are trapped and detected. A larger number of structurally informative fragments is generated upon irradiation with infrared photons relative to the CAD method because of the further excitation of primary fragment ions upon photoabsorption. SWIFT wave forms are successfully utilized to determine the extent of excitation of primary fragment ions as well as prove/disprove dissociation pathways of a variety of ions such as macrolide antibiotics and hydrogen-bonded complexes.

Interaction of 2-halogenated dATP analogs (F, Cl, and Br) with human DNA polymerases, DNA primase, and ribonucleotide reductase

Recently, 2-halogenated deoxyadenosine analogs (F, Cl, and Br) have been shown to have antitumor activity. These analogs are phosphorylated by cells and are believed to exert their cytotoxic action at the nucleoside triphosphate level. In this work the interaction of these nucleoside triphosphate analogs with potential targets, such as DNA polymerase alpha, beta, and gamma, DNA primase, and ribonucleotide reductase was examined in detail. All of these compounds competitively inhibited the incorporation of dAMP into DNA by DNA polymerase alpha, beta, or gamma. F-dATP was able to completely substitute for dATP using DNA polymerase alpha and gamma, but not with DNA polymerase beta. Cl-dATP and Br-dATP substituted poorly for dATP using DNA polymerase alpha and beta. Extension of a 32P-labeled primer by DNA polymerase alpha, beta, or gamma on a single-stranded M13 template showed that these compounds were incorporated into the 3' end of the growing DNA chain and that elongation beyond the incorporated analogs was significantly retarded for Cl-dATP and Br-dATP using either DNA polymerase alpha or beta. DNA primase using poly(dC) as template was inhibited by these compounds at a concentration 4 to 5 times greater than that required for 2-F-araATP. The 2-halogenated dATP analogs were potent inhibitors of ADP reduction by ribonucleotide reductase. In conclusion, the cytotoxic action of 2-Cl-deoxyadenosine and 2-Br-deoxyadenosine may partially be mediated through the mechanism of "self-potentiation," by depression of the deoxynucleoside triphosphate pools due to inhibition of ribonucleotide reductase, which would facilitate their incorporation into DNA and result in the inhibition of DNA synthesis.