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Biomedical subjects

J Lin

Publications and source records attributed to J Lin.

At least 109 records · Page 6Linked to original sources
PubMed2001

Bending strength and holding power of tibial locking screws.

The bending strength and holding power of two types of specially designed tibial locking devices, a both-ends-threaded screw and an unthreaded bolt, were studied and compared with four types of commercially available tibial interlocking screws: Synthes, Howmedica, Richards, and Osteo AG. To test bending strength, the devices were inserted into a high molecular weight polyethylene tube and loaded at their midpoint by a materials testing machine to simulate a three point bending test. Single loading yielding strength and cyclic loading fatigue life were measured. To test holding power, the devices were inserted into tubes made of polyurethane foam, and their tips were loaded axially to measure pushout strength. The devices were tested with two different densities of foam materials and two different sizes of pilot holes. Insertion torque and stripping torque of the screws were measured first. Pushout tests were performed with each screw inserted with a tightness equal to 60% of its stripping torque. Test results showed that the yielding strength and the fatigue life were related closely to the inner diameter of the screws. The stripping torque predicted the pushout strength more reliably than did the insertion torque. All tested devices showed greater holding power in the foam with the higher density and with the smaller pilot holes. The both-ends-threaded screw had the highest pushout strength and a satisfactory fatigue strength. The unthreaded bolt had the highest fatigue strength but only fair holding power. Clinical studies of the use of these two types of locking devices are worthwhile.

Bone Screws↗
PubMed2001

Benchmarking the endodontic literature on MEDLINE.

The purpose of this study was to identify and quantify the endodontic literature available for clinical decision making. A search strategy based on Medical Subject Headings for endodontics was developed to examine MEDLINE. The identified articles were limited to human subjects and English. Sensitive and specific methodological search filters identified four categories of information: etiology, diagnosis, therapy, and prognosis. The results were then subdivided by year to identify trends. Between 1990 and 1998 MEDLINE identified 3,152 articles published in English on endodontics in humans. The number of articles per year (mean +/- SD) for sensitive and specific searches was etiology (28+/-10, 1+/-2), diagnosis (38+/-11, 1+/-1), therapy (59+/-15, 3+/-3), and prognosis (40+/-13, 10+/-5), respectively. The number of articles in each category increased by 1 to 3% each year. There were 150 articles/yr in endodontics in at least 120 journals cited on MEDLINE on which to base clinical decisions.

Analysis of Variance↗
PubMed2001

Unreamed locked tight-fitting nailing for acute tibial fractures.

OBJECTIVES: Treatment of tibial fractures by unreamed locked nailing with loose-fitting nails has previously been shown to be associated with a low union rate and high implant failure rate. This report describes the authors' experience in using tight-fitting nails that were relatively larger than loose-fitting nails. DESIGN: Prospective cohort study. SETTING: University medical center. PATIENTS: Forty-eight consecutive patients with fifty-two tibial fractures (excluding open IIIC fractures and those with bone loss) were studied: thirty-four men and fourteen women, with a mean age of 38 years. There were twenty-five closed fractures, nine Type I, eight Type II, four Type IIIA, and six Type IIIB open fractures. INTERVENTION: Unreamed nailing with tight-fitting nails using the Russell-Taylor system. OUTCOME MEASURES: Union rate, time to union, complication rate, and functional recovery, as well as nailing time, hospital time, and crutch-walking time were recorded. RESULTS: Union occurred in forty-eight of fifty-two fractures (92%) with a mean time to union of 18.2 weeks. Compartment syndrome occurred in three patients. Deep infection occurred in one Type II and one Type IIIB open fracture. Four fractures required additional exchange nailing or bone grafting to achieve union: one Type II, one Type IIIA, and two Type IIIB open fractures. Three malalignments resulted from operative technical error. The rate of both intraoperative bony split and screw breakage was 3.8% (2 of 52), but neither complication interfered with fracture healing. Recovery of joint motion was essentially normal in those patients without knee or ankle injury. CONCLUSIONS: Unreamed locked nailing with tight-fitting nails can produce satisfactory clinical results for acute tibial fractures. It has the advantages of technical simplicity and an acceptable risk of implant failure.

Acute Disease↗
PubMed2001

Heparin-binding epidermal growth factor-like growth factor is an autocrine mediator of human prostate stromal cell growth in vitro.

PURPOSE: The physiological mechanisms by which soluble mediators of cell proliferation and survival alter expansion of the prostatic stroma in benign prostatic hyperplasia are poorly understood. We recently identified heparin-binding epidermal growth factor like growth factor (HB-EGF) as a product predominantly of the smooth muscle cell compartments of the adult human prostate. We assess the potential role of this growth factor as a stromal cell regulator. MATERIALS AND METHODS: Primary cultures of desmin and alpha-actin positive human prostate stromal cells were shown to express several cell associated HB-EGF isoforms as well as the primary cognate HB-EGF receptor, ErbB1/HER1, suggesting the existence of an autocrine or juxtacrine regulatory loop. The related receptor tyrosine kinase, ErbB2/HER2, was also expressed as assessed by reverse transcriptase (RT) polymerase chain reaction (PCR). HB-EGF messenger RNA levels in human prostate stromal cells increased modestly (70%) in response to a repetitive mechanical stimulus, a lower response than has been reported for neonatal rat bladder smooth muscle cells, in which HB-EGF was originally identified as a mechanically responsive gene. RESULTS: HB-EGF, epidermal growth factor and basic fibroblast growth factor stimulated human prostate stromal cell growth, while a specific antagonist of HB-EGF, [Glu52]-diphtheria toxin/CRM197, inhibited human prostate stromal growth in serum-free medium by a mechanism that did not involve increased apoptosis. A function blocking antibody against CD9/DRAP27/MRP-1, a cell surface binding partner of the membrane form of HB-EGF, also stimulated human prostate stromal cell proliferation. CONCLUSIONS: HB-EGF is an endogenously produced human prostate stromal cell growth factor and, thus, may have a role as a physiologically relevant autocrine or juxtacrine mediator of stromal expansion in benign prostatic hyperplasia.

Adult↗
PubMed2001

Shotgun optical maps of the whole Escherichia coli O157:H7 genome.

We have constructed NheI and XhoI optical maps of Escherichia coli O157:H7 solely from genomic DNA molecules to provide a uniquely valuable scaffold for contig closure and sequence validation. E. coli O157:H7 is a common pathogen found in contaminated food and water. Our approach obviated the need for the analysis of clones, PCR products, and hybridizations, because maps were constructed from ensembles of single DNA molecules. Shotgun sequencing of bacterial genomes remains labor-intensive, despite advances in sequencing technology. This is partly due to manual intervention required during the last stages of finishing. The applicability of optical mapping to this problem was enhanced by advances in machine vision techniques that improved mapping throughput and created a path to full automation of mapping. Comparisons were made between maps and sequence data that characterized sequence gaps and guided nascent assemblies.

Contig Mapping↗
PubMed2001

A novel method for beat-to-beat detection of ventricular late potentials.

A novel method for beat-to-beat detection of ventricular late potentials (VLP) from high-resolution electrocardiograms (ECGs) is presented. ECG signals from the X lead are first filtered using a bandpass filter, and then a time-sequence adaptive filter, to improve its signal-to-noise ratio. Eight features are extracted using wavelet transform, from the VLP time-frequency distribution of the filtered ECG signals, and used as inputs of specially designed artificial neural network for VLP recognition. The artificial neural network was trained and tested using clinical data, respectively. The results show that the presented method can detect beat-to-beat-based VLP with sensitivity of 80% and specificity of 77%, and the detection accuracy is 78%.

Action Potentials↗
PubMed2001

A case of Kaposi's sarcoma associated with pemphigoid nodularis.

Pemphigoid nodularis is a rare variant of bullous pemphigoid. Bullous pemphigoid complicated by internal malignancy has been well documented. There have been only a few reported cases of bullous pemphigoid associated with Kaposi's sarcoma. We described a case of pemphigoid nodularis who later developed Kaposi's sarcoma that might be related to immunosupressive therapy, a situation that has not been reported previously.

Aged↗
PubMed2001

Characterization of mucins in human middle ear and Eustachian tube.

Mucins are important glycoproteins in the mucociliary transport system of the middle ear and Eustachian tube. Little is known about mucin expression within this system under physiological and pathological conditions. This study demonstrated the expression of MUC5B, MUC5AC, MUC4, and MUC1 in the human Eustachian tube, whereas only MUC5B mucin expression was demonstrated in noninflamed middle ears. MUC5B and MUC4 mucin genes were upregulated 4.2- and 6-fold, respectively, in middle ears with chronic otitis media (COM) or mucoid otitis media (MOM). This upregulation of mucin genes was accompanied by an increase of MUC5B- and MUC4-producing cells in the middle ear mucosa. Electron microscopy of the secretions from COM and MOM showed the presence of chainlike polymeric mucin. These data indicate that the epithelium of the middle ear and Eustachian tube expresses distinct mucin profiles and that MUC5B and MUC4 mucins are highly produced and secreted in the diseased middle ear. These mucins may form thick mucous effusion in the middle ear cavity and compromise the function of the middle ear.

Aged↗
PubMed2001

Anatomical relationships between Sylvian fissure and the sphenoid ridge.

During pterional craniotomy, the sphenoid ridge is resected to facilitate the dissection of the arachnoid in the Sylvian fissure. It is a common intra-operative perception that a deep sphenoid ridge often accompanies a shallow fissure. We explored this unique relationship between the sphenoid ridge and the Sylvian fissure. We studied 46 fresh adult cadavers and measured the depth of both the sphenoid ridges and the Sylvian fissure. The deepest portion of the sphenoid ridge was determined and its depth measured by using a narrow ruler with a sliding gauge. The depth of the Sylvian fissure was measured from the middle cerebral artery bifurcation perpendicularly to the surface of the temporal pole where the arachnoid was cut. An inverse relationship exists between the Sylvian fissure and the sphenoid ridge. The depth of the sphenoid ridge averages 7.28 mm +/- 0.3 mm while the depth of the Sylvian fissure averages 9.0 mm +/- 0.4 mm. Approximately 25% of studied population have deep ridges, i.e. greater than 10 mm, and approximately 25% have shallow ridges, i.e. less than 4 mm. The extent to which the sphenoid ridge projects into the Sylvian fissure determines the depth of the Sylvian fissure thus explaining their inverse relationship. Importantly, encountering a shallow sphenoid ridge during surgery most likely will result in the dissection of a deep Sylvian fissure while a deep ridge predicts a shallow fissure.

Anthropometry↗
PubMed2001

Two-stage exchange hip arthroplasty for deep infection.

Although the risk of infection after total hip arthroplasty has decreased over the last three decades with the use of prophylactic antibiotics, laminar airflow operating rooms and whole-body exhaust suites, deep infection after total hip arthroplasty remains a serious complication. Significant morbidity to the patient and the cost to the health care system remain. During this period of time, diagnostic techniques also have improved including the use of polymerase chain reaction amplification. Treatment options now include: suppressive antibiotics, irrigation and debridement with retention of components, one-stage reimplantation, two-stage reimplantation, and salvage procedures. Based on the medical literature, the successful eradication of a total joint replacement infection with a two-stage reimplantation protocol is over 90% while the success rate with a one-stage protocol is approximately 80%. These success rates may decline however as the prevalence of antibiotic resistant organisms increases. Current controversies regarding two-stage reimplantation protocols include: duration of intravenous antibiotic therapy, timing of the reimplantation, the use of allograft bone in the reconstruction, the choice of fixation (cement versus cementless), and the use of antibiotic-loaded cement spacers.

Anti-Bacterial Agents↗
PubMed2001

Intraarticular osteoid osteoma: sonographic findings in three patients with radiographic, CT, and MR imaging correlation.

OBJECTIVE: Intraarticular osteoid osteoma often has subtle radiographic findings and nonspecific clinical features; further diagnostic workup of unexplained joint pain may involve musculoskeletal sonography. We describe the sonographic features of intraarticular osteoid osteoma in three consecutive patients with radiographic, CT, and MR imaging correlation. CONCLUSION: The sonographic findings of painful cortical irregularity and focal synovitis should raise the possibility of intraarticular osteoid osteoma, prompting the search for characteristic findings on correlative imaging studies.

Adult↗
PubMed2001

A genome scan for type 2 diabetes susceptibility loci in a genetically isolated population.

A total of 896 individuals of Ashkenazi Jewish descent were ascertained in Israel from 267 multiplex families, including 472 sib-pairs affected with type 2 diabetes. A genome-wide scan with average marker spacing of 9.5 cM revealed five regions on four chromosomes (4q, 8q, 14q, and 20q) that exhibited nominal evidence for linkage (P < 0.05). The highest observed nonparametric linkage Z score was 2.41 (equivalent to a logarithm of odds score of 1.26) at marker D4S1501. A maximal signal, with a Z score of 2.05, was observed on chromosome 20 near marker D20S195, and another on 20p near marker D20S103 (Z 1.80). A single marker on chromosome 8 (D8S593) and two adjacent markers on chromosome 14 (D14S749 and D14S605) also attained evidence of linkage. To explore the hypothesis that the signals on chromosomes 4 and 20 are differentially attributable to variation in BMI or age of onset, an ordered subset analysis was conducted. This analysis revealed that only when the families were ranked by BMI (in increasing order) did a subset attain nominal significance, and only for chromosome 4. The findings reported here lend credence to the hypothesis, now supported by four studies of Caucasian populations and most recently by a combined analysis of 1,852 pedigrees, that a type 2 diabetes susceptibility locus resides on chromosome 20q. This population, because of its unique genetic attributes, may facilitate identification of this and other genes contributing to type 2 diabetes.

Body Mass Index↗
PubMed2001

Mutations in the coding region of the neurogenin 3 gene (NEUROG3) are not a common cause of maturity-onset diabetes of the young in Japanese subjects.

Mutations in transcription factors that play a role in the development of the endocrine pancreas, such as insulin promoter factor-1 and NeuroD1/BETA2, have been associated with diabetes. Cell type-specific members of the basic helix-loop-helix (bHLH) family of transcription factors play essential roles in the development and maintenance of many differentiated cell types, including pancreatic beta-cells. Neurogenin 3 is a bHLH transcription factor that is expressed in the developing central nervous system and the embryonic pancreas. Mice lacking this transcription factor fail to develop any islet endocrine cells and die postnatally from diabetes. Because neurogenin 3 is required for the development of beta-cells and other pancreatic islet cell types, we considered it a candidate diabetes gene. We screened the coding region of the human neurogenin 3 gene (NEUROG3) for mutations in a group of unrelated Japanese subjects with maturity-onset diabetes of the young (MODY). We found three sequence variants: a deletion of 2-bp in the 5'-untranslated region (NEUROG3-g.-44-45delCA), a G-to-A substitution in codon 167 (g.499G/ A), resulting in a Gly-to-Arg replacement (G/R167), and a T-to-C substitution in codon 199 (g.596T/C), resulting in a Phe/Ser polymorphism F/S199. These polymorphisms were not associated with MODY, thereby suggesting that mutations in NEUROG3 are not a common cause of MODY in Japanese patients.

Amino Acid Substitution↗
PubMed2001

Regulation of the pancreatic pro-endocrine gene neurogenin3.

Neurogenin3 (ngn3), a basic helix-loop-helix (bHLH) transcription factor, functions as a pro-endocrine factor in the developing pancreas: by itself, it is sufficient to force undifferentiated pancreatic epithelial cells to become islet cells. Because ngn3 expression determines which precursor cells will differentiate into islet cells, the signals that regulate ngn3 expression control islet cell formation. To investigate the factors that control ngn3 gene expression, we mapped the human and mouse ngn3 promoters and delineated transcriptionally active sequences within the human promoter. Surprisingly, the human ngn3 promoter drives transcription in all cell lines tested, including fibroblast cell lines. In contrast, in transgenic animals the promoter drives expression specifically in regions of ngn3 expression in the developing pancreas and gut; and the addition of distal sequences greatly enhances transgene expression. Within the distal enhancer, binding sites for several pancreatic transcription factors, including hepatocyte nuclear factor (HNF)-1 and HNF-3, form a tight cluster. HES1, an inhibitory bHLH factor activated by Notch signaling, binds to the proximal promoter and specifically blocks promoter activity. Together with previous genetic data, these results suggest a model in which the ngn3 gene is activated by the coordinated activities of several pancreatic transcription factors and inhibited by Notch signaling through HES1.

Animals↗