Biomedical subjects
Publications and source records attributed to S Feng.
Craniosynostosis is the term that designates premature fusion of one or more cranial sutures that causes severe cranial deformities. The clinical features and the operative technique were introduced and the etiology and the key points for a successful operation were discussed in this paper.
Solution structures of two Src homology 3 (SH3) domain-ligand complexes have been determined by nuclear magnetic resonance. Each complex consists of the SH3 domain and a nine-residue proline-rich peptide selected from a large library of ligands prepared by combinatorial synthesis. The bound ligands adopt a left-handed polyproline type II (PPII) helix, although the amino to carboxyl directionalities of their helices are opposite. The peptide orientation is determined by a salt bridge formed by the terminal arginine residues of the ligands and the conserved aspartate-99 of the SH3 domain. Residues at positions 3, 4, 6, and 7 of both peptides also intercalate into the ligand-binding site; however, the respective proline and nonproline residues show exchanged binding positions in the two complexes. These structural results led to a model for the interactions of SH3 domains with proline-rich peptides that can be used to predict critical residues in complexes of unknown structure. The model was used to identify correctly both the binding orientation and the contact and noncontact residues of a peptide derived from the nucleotide exchange factor Sos in association with the amino-terminal SH3 domain of the adaptor protein Grb2.
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A common RXL motif was found in proline-rich ligands that were selected from a biased combinatorial peptide library on the basis of their ability to bind specifically to the SH3 domains from phosphatidylinositol 3-kinase (PI3K) or c-Src. The solution structure of the PI3K SH3 domain complexed to one of these ligands, RKLPPRPSK (RLP1), was determined. Structure-based mutations were introduced into the PI3K SH3 domain and the RLP1 ligand, and the influence of these mutations on binding was evaluated. We conclude that SH3 domains recognize proline-rich motifs possessing the left-handed type II polyproline (PPII) helix conformation. Two proline residues directly contact the receptor. Other prolines in the ligands appear to function as a molecular scaffold, promoting the formation of the PPII helix. Three nonproline residues consisting of combinations of arginine and leucine interact extensively with the SH3 domain and appear to confer ligand specificity.
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Forty-one participants (mean age 69 +/- 5.6 years) were examined by fully automatic blood pressure monitor and Doppler echocardiography to gain information on the ambulatory blood pressure and the left ventricular structure and function in isolated systolic hypertension. Cumulative sum (cusum)-derived statistics was used to quantify circadian blood pressure rhythm and 24-h blood pressure levels were defined as mean blood pressure values during 24 h, waking (06:00-22:00 h) and sleeping (22:00-06:00 h) periods, respectively. Most of the derivatives of ambulatory blood pressure, including cusum-derived statistics and 24-h blood pressure levels, were significantly related with the left ventricular structural (left ventricular posterior wall and interventricular septum thickness) and functional (acceleration time in the left ventricular outflow tract and early diastolic deceleration time) indexes. Among the left ventricular structural and functional indexes, interventricular septum thickness at end diastole had the strongest correlation with sleeping diastolic mean blood pressure (r = 0.41, P < 0.01), left ventricular posterior wall at end diastole, the best with 24-h systolic mean blood pressure (r = 0.41, P < 0.01), acceleration time the strongest with systolic cusum-derived circadian alteration magnitude (r = 0.49, P < 0.01) and early diastolic deceleration time the greatest with diastolic cusum-derived trough blood pressure (r = 0.45, P < 0.01). We conclude that left ventricular structural changes rely on 24-h systolic and diastolic blood pressure levels, whereas left ventricular functional variations may be more dependent upon circadian blood pressure rhythm in elderly patients with isolated systolic hypertension.
In last six years, 51 cases (34 males, 17 females) of orbital deformities caused by fracture were treated. According to careful examinations, x-ray and CT scan, the operation plan was made. The coronal incision or plus lower eyelid incision were employed. Subperiosteal dissection began from the upper margin of the orbit to release input soft tissue and reposition the eyeball. Rib bone was grafted for orbital defects. Canthoplasty was used if necessary. The surgical results were satisfactory.
Since 1986, we have treated 302 cases with hepatic and abdominal hydatid cyst (361 cysts) by the method of percutaneous puncture, drainage and curettage combined with systemic drug and local drug administration with 5 years' follow-up. The rate of success of percutaneous puncture, aspiration, drainage and curettage was 99%. Only one case presented allergic reaction. At 6 months after the PPDC, 97.2% (212/218) of the cysts had stopped growth. One year later, 84.4% (130/154) of the cysts had disappeared. Five years' follow-up revealed that 77.8% (14/18) of the cysts had disappeared. All of the above-mentioned cases have recovered except for two cases suffered from recurrence of primary cysts resulting from a drop of the cannulas. No serious complications or death had been found.
Fifteen patients with micrognathia and obstructive sleep apnea syndrome (OSAS) are presented. All patients were evaluated before and after surgery by physical examinations, cephalometric, fibroptic pharyngoscopy and oxygen saturation (SaO2). A method that allows isolated advancement of the genial tubercle and genioglossus muscle is described. The operation could enlarge the pharyngeal airway space at the base of the tongue (P < 0.05), increase SaO2 and decrease MP-H (P < 0.05) so that the symptoms of OSAS improved or disappeared. The facial symmetry and chin prominence also improved significantly. This method is simple and effective for the treatment of OSAS due to micrognathia and obviates the need for intermaxillary fixation. But it is not indicated for patients with severe malocclusion or airway obstruction on more than one sites.
Crouzon syndrome is one of craniosynostosis syndromes (or craniofacial dysostosis). It consists of multiple craniofacial deformities including severe midface retrusion, exorbitism and close bite. In 11 cases LeFort III advancement osteotomy to move the midface segments was performed in past eight years. We evaluate the result of reconstructive and postoperative aesthetic improvement using measurements of lateral cephalograms and exophthalmetry. Changes in midface horizontal view are obvious postoperatively, and SNA is increased from 70.9 degree to 74.5 degree, SNB decrease from 85.1 degree to 80.8 degree, and ANB increase from -14.2 degree to -6.3 degree. Midface segment is brought forward (average 10mm) and downward (average 2mm) postoperatively. The distance from the posterior nasal spine to the posterior pharyngeal wall on cephalograms is increased from 9.1mm to 19mm. Complications are discussed.
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