Biomedical subjects

J C Post

Publications and source records attributed to J C Post.

At least 37 records · Page 2Linked to original sources

PubMed1997

Pediatric respiratory papillomatosis: prognostic role of viral typing and cofactors.

Children with recurrent respiratory papillomatosis vary greatly in their clinical disease course. Many have mild disease with eventual remission while others present with an early aggressive airway obstructive course. This study consisted of 24 pediatric patients whose specimens underwent polymerase chain reaction analysis for cytomegalovirus (CMV), herpes simplex virus (HSV), and human papillomavirus (HPV) type. Nineteen of 24 specimens contained enough DNA for this study. None of the specimens were found to contain DNA from HPV-16, -18, -31, -33; CMV; or HSV, which contrasts with our previous findings in adults. Ten patients were infected by HPV-11 and seven of these underwent tracheotomy because of an aggressive tumorigenic clinical course. Nine patients were infected by HPV-6 alone of whom only two required a tracheotomy (P = 0.05, Fisher's Exact Test). The early airway obstructive course associated with HPV-11, however, had no bearing on achieving eventual disease remission, with decannulation achieved in eight of nine children.

Adult↗

PubMed1996

Munchausen syndrome by proxy complicating ear surgery.

Munchausen syndrome by proxy (MSBP) is a form of child abuse in which a parent or caretaker produces or simulates illness in a child. Often great lengths are undertaken to diagnose and treat the myriad of symptoms and problems in these children. Unnecessary examinations, treatments, and hospitalizations ensure. Unfortunately, some victims of this syndrome die. Munchausen syndrome by proxy is a form of child abuse and should be reported appropriately. The diagnosis of MSBP is difficult to make and must be done with caution as the implications for those involved are serious. Therefore, care must be taken in properly identifying cases. We present a case of MSBP complicating the postoperative course of a boy after undergoing ear surgery for cholesteatoma. Characteristics and potential clues to the diagnosis of MSBP are discussed. The goal of our article is to inform otolaryngologists of this syndrome so they may develop a high index of suspicion to better detect its occurrence.

Child, Preschool↗

PubMed1996

Pediatric fiberoptic laser rigid bronchoscopy.

Use of the fiberoptic laser for treatment of tracheobronchial lesions in the adult is well established. However, there is a paucity of experience with the fiberoptic laser in the pediatric airway. Tracheal obstruction caused by granulation tissue or stenosis, as is often seen in children, may be effectively treated with this approach. This article documents the successful use as well as the technologic advantage of the flexible fiberoptic laser systems, primarily the potassium titanyl phosphate (KTP) laser, combined with standard pediatric rigid bronchoscopic equipment in 73 procedures involving 52 children (43 children younger than five years. with an average age of 21 months). Visualization was excellent, assisted or spontaneous ventilation was well maintained, and complications were few.

Adolescent↗

PubMed1996

Hereditary pancreatitis is caused by a mutation in the cationic trypsinogen gene.

Hereditary pancreatitis (HP) is a rare, early-onset genetic disorder characterized by epigastric pain and often more serious complications. We now report that an Arg-His substitution at residue 117 of the cationic trypsinogen gene is associated with the HP phenotype. This mutation was observed in all HP affected individuals and obligate carriers from five kindreds, but not in individuals who married into the families nor in 140 unrelated individuals. X-ray crystal structure analysis, molecular modelling, and protein digest data indicate that the Arg 117 residue is a trypsin-sensitive site. Cleavage at this site is probably part of a fail-safe mechanism by which trypsin, which is activated within the pancreas, may be inactivated; loss of this cleavage site would permit autodigestion resulting in pancreatitis.

Arginine↗

PubMed1996

A gene for hereditary pancreatitis maps to chromosome 7q35.

BACKGROUND & AIMS: Hereditary pancreatitis (HP) is an autosomal-dominant disorder with incomplete penetrance characterized by recurrent bouts of severe epigastric pain with onset usually at 5-10 years of age. A genetic linkage study was designed to identify the HP gene. METHODS: A 500-member pedigree was constructed from a U.S. kindred centered in eastern Kentucky and western Virginia. A genome-wide search strategy was employed using a 36-member subset of this family to determine the genetic locus for HP. Testing for linkage to microsatellite loci was performed at 20-cM intervals. RESULTS: Linkage was established between the HP phenotype and chromosome 7q in this subset of the family. Modeled as an autosomal dominant disorder with 80% penetrance, a maximal multipoint logarithm of the odds score of 4.3 was obtained using a four-point analysis consisting of markers D7S684, D7S661, D7S505, and the HP locus. Two microsatellite markers, D7S661 and D7S505, that correspond to the 7q35 region of chromosome 7 spanning a 6-cM region did not evidence obligate recombinations with HP. The centromeric and telomeric limits are defined by recombinations at D7S684 and D7S483, respectively, which generates a 19-cM locus for HP. Utilizing family members from the extended pedigree, a break in the high-risk haplotype between D7S684 and D7S661 was observed, which suggests it may be possible to exclude an additional 8 cM from the HP locus. A maximal pairwise logarithm of the odds score of 4.73 at a recombination fraction of theta at D7S684 was obtained with the addition of these extended family members. CONCLUSIONS: Linkage of HP to 7q35 represents a major advancement in our understanding of the genetic basis of this disorder.

Chromosome Mapping↗

PubMed1996

Laryngotracheal reconstruction using microplates in a porcine model with subglottic stenosis.

Current techniques of laryngotracheal reconstruction require a choice between prolonged stenting (conventional technique) or short-term stenting with maintenance of sedation and paralysis until the airway has stabilized (single-stage laryngotracheal reconstruction). An alternative method is proposed using microplates to provide immediate airway stabilization without stenting. This study was designed to evaluate the long-term effects of microplate repair of stenosis of the subglottis and trachea on the growing larynx. Subglottic stenosis was produced in piglets using a transoral endoscopic technique. Eight animals underwent repair of the stenosis using an anterior cricoid split with microplate distraction and stabilization of the cricoid cartilage and first tracheal ring. The distraction was maintained and airway growth continued for the duration of this study. However, with growth of the larynx the plates migrated away from their original position. In 50% of the animals followed up for 90 days the plates migrated into the airway lumen. This study suggests that rigid distraction of the stenotic airway with microplates is a viable alternative to more traditional methods of repair. However, plate removal at some interval after surgery is required in the growing larynx in order to prevent migration of the plate into the airway.

Animals↗

PubMed1996

Three-dimensional respiratory-gated MR angiography of coronary arteries: comparison with conventional coronary angiography.

OBJECTIVE: MR coronary angiography is most often performed using two-dimensional techniques. Although three-dimensional (3D) acquisitions do have important advantages, they take too long for a single breath-hold and are thus susceptible to respiratory motion artifacts. The purpose of this study was to investigate the accuracy of a unique respiratory-gated 3D MR angiographic technique in identifying the proximal coronary arteries in patients suspected of having coronary artery disease. In addition, we investigated the capability of this technique to detect proximal stenoses. SUBJECTS AND METHODS: We performed a prospective blinded study in 20 patients who were referred for conventional coronary angiography. A cardiac-gated 3D gradient-echo sequence with fat suppression was used. Retrospective respiratory gating was performed using navigator echoes of the diaphragm position. Using multiplanar reformatting, two independent readers blindly analyzed the data sets for visualization of major coronary arteries, lengths of imaged segments, and detection of significant stenoses (> 50% occlusion of the luminal diameter by conventional angiography). RESULTS: Seventy-seven of 80 (96%) coronary arteries were positively identified. In one patient, an anomalous coronary anatomy was readily identified and confirmed by conventional angiography. The average lengths of the imaged segments of the right, left main, left anterior descending, and left circumflex coronary arteries were 58 +/- 13 mm, 9 +/- 5 mm, 59 +/- 16 mm, and 24 +/- 10 mm, respectively. Overall sensitivity for the detection of stenoses was low (38%), with a specificity of 95%. Interobserver agreement was 0.92, with a kappa value of 0.65. CONCLUSION: Respiratory-gated 3D MR angiography allows accurate identification of proximal coronary arteries and may be valuable for 3D imaging of coronary anomalies. Further technical improvements are required to enhance the value of the technique in detecting stenoses.

Adult↗

PubMed1996

Coronary imaging using MRI.

Without use of ionizing radiation and injection of contrast material magnetic resonance imaging (MRI) can be applied to generate signal from flowing blood and create tomographic images of the bloodstream in coronary arteries, which resemble conventional contrast enhanced X-ray angiograms. The tortuosity, small diameter and motion of the coronary arteries provided technically demanding problems, which had to be solved before MR coronary angiography became realistic. Faster pulse sequences, dedicated radiofrequency receiver coils, cardiac and respiratory gating techniques were introduced and are still in the process of constant development to improve the quality of the images. To date, most clinical experience has been obtained using 2D approaches necessitating repetitive breath-holds to encompass the coronary artery tree. A substantial part of the proximal and middle parts of the coronary arteries can be visualized, which has proven to be accurate in identifying anomalous coronary anatomy and patency of proximal coronary artery bypass grafts. However, the technique is currently not sensitive enough to reliably detect coronary artery stenoses. Another approach is a single acquisition respiratory gated 3D technique which is less operator and patient dependent, requires less imaging time for an entire coronary protocol and is more comfortable for the patient than the 2D breath-hold approach. Initial experience demonstrates the capability to identify the major epicardial coronary vessels. But here too, further development is required to demonstrate coronary stenoses. A unique feature of MR imaging is the feasibility to non-invasively quantitate flow in the coronary arteries. This offers the potential to selectively determine the flow reserve of coronary arteries and to assess the functional and physiological implications of moderately severe stenoses. It can be envisaged that, although currently not apt to replace conventional coronary angiography, MR coronary angiography and flow measurement will become of use in the evaluation of specific, well defined clinical issues in coronary artery disease.

Artifacts↗

PubMed1995

Magnetic resonance angiography of anomalous coronary arteries. A new gold standard for delineating the proximal course?

BACKGROUND: The clinical significance of anomalously originating coronary arteries depends on their proximal course. Diagnosis of this course by conventional x-ray coronary angiography alone may be equivocal. We postulated that with fast magnetic resonance (MR) angiography, accurate detection of anomalous coronary arteries and unambiguous delineation of their proximal course is feasible. METHODS AND RESULTS: In a selected group of 38 patients, 19 of them having an anomalously originating coronary artery, a fast MR angiographic technique was used to study the proximal coronary anatomy. Blinded analysis of randomly ordered MR studies was performed independently by two observers. Both origin and proximal course of the coronary arteries were defined. Two cardiologists reviewed all x-ray coronary angiograms. After the separate analyses, a final consensus result was defined for each patient. In 37 patients, successful MR coronary angiography could be performed. Interobserver agreement for determining both origin and proximal course was 100%. An x-ray coronary angiogram was available in 36 patients. In 3 patients (all with an anomalous left main coronary artery originating from the right aortic sinus), there was disagreement about the proximal course between the results of MR and x-ray coronary angiography. Review of these cases demonstrated that MR angiography had unambiguously visualized the proximal coronary artery course, whereas the results of x-ray angiography had been equivocal. Thus, sensitivity and specificity for detecting anomalous coronary arteries and delineating their proximal course were 100%. CONCLUSIONS: These data suggest that fast MR angiography is highly accurate in determining the origin and delineating the proximal course of anomalous coronary arteries, even in those cases in which x-ray coronary angiographic diagnosis is difficult or even erroneous.

Coronary Angiography↗

PubMed1995

Identification of a patient with Streptococcus pneumoniae bacteremia and meningitis by the polymerase chain reaction (PCR).

A polymerase chain reaction (PCR) assay based on the penicillin-binding protein gene PBP2B identified the presence of DNA specific for Streptococcus pneumoniae in the serum and CSF of a patient with culture-proven bacteremia and meningitis. Positive signals were seen to dilutions of 1:125 and 1:390,625 for the blood and CSF specimens, respectively. Potential advantages of PCR over conventional culture include exquisite sensitivity, faster results and the ability to identify the organisms by the presence of species-specific DNA even in patients pretreated with antibiotics.

Aminoacyltransferases↗

PubMed1995

Protocol for two-dimensional magnetic resonance coronary angiography studied in three-dimensional magnetic resonance data sets.

The purpose of this study was to develop a standardized method of 2D MRA of the proximal 50 mm of the major epicardial coronary arteries. Therefore the efficacy of fixed imaging planes (transverse, coronal, sagittal, 30-degree RAO equivalent, and 60-degree LAO equivalent) in imaging coronary arteries was compared to that of oblique planes defined by the operator on a previously obtained image. 3D data sets obtained by a respiratory-gated 3D MRA method in eight patients with a mean age of 57 years were studied by multiplanar reformatting. Efficacy of planes was expressed as an IOE. Fixed transverse imaging planes proved to be equally efficacious as operator-defined planes in imaging the left main (IOE 2.2 +/- 1.0 vs 2.2 +/- 0.9, p = NS) and LAD (IOE 6.0 +/- 1.9 vs 8.2 +/- 2.0, p = NS). Operator-defined planes were superior to fixed imaging planes in imaging the RCA (IOE 6.3 +/- 1.2 vs 3.5 +/- 1.2, p < 0.001) and the LCx (IOE 6.2 +/- 2.3 vs 4.8 < 2.3, p < 0.05). On the basis of these results, a standardized 2D MRA protocol for the proximal coronary arteries was proposed. Pitfalls in interpretation of coronary MRA images were discussed.

Aged↗

PubMed1995

Crouzon syndrome: mutations in two spliceoforms of FGFR2 and a common point mutation shared with Jackson-Weiss syndrome.

Dominant mutations in the fibroblast growth factor receptor 2 (FGFR2) gene have been recently identified as causes of four phenotypically distinct craniosynostosis syndromes, including Crouzon, Jackson-Weiss, Pfeiffer, and Apert syndromes. These data suggest that the genetics of the craniosynostosis syndromes is more complex than would be expected from their simple autosomal-dominant inheritance pattern. Identical mutations in the FGFR2 gene have been reported to cause both Pfeiffer and Crouzon syndrome phenotypes. We now report the finding of a mutation in exon IIIc of the FGFR2 gene in a kindred affected with Crouzon syndrome (C1043 to G; Ala344Gly) that is identical to the mutation previously associated with Jackson-Weiss syndrome. We also report finding in a Crouzon kindred a mutation in the 3' end of exon IIIu (formerly referred to as exon 5, exon 7, or exon U) (A878 to C; Gln289Pro) which encodes the amino terminal portion of the Ig-like III domain of the FGFR2 protein. This exon is common to both the FGFR2 and the KGFR spliceoforms of the FGFR2 gene, unlike all previously reported Crouzon mutations, which have been found only in the FGFR2 spliceoform. These findings reveal further unexpected complexity in the molecular genetics of these craniosynostosis syndromes. The data implies that second-site mutations in FGFR2 itself (outside of exon IIIc) or in other genes may determine specific aspects of the phenotypes of craniosynostosis syndromes.

Base Sequence↗

PubMed1995

Influenza A virus--induced acute otitis media.

To better understand the significance of viral upper respiratory tract infections in the pathogenesis of acute otitis media (OM), 27 adults underwent intranasal inoculation with influenza A virus. Monitoring consisted of antibody titer determination, tympanometry, and otoscopy. Microbiologic analysis consisted of cultures and polymerase chain reaction (PCR)-based detection for influenza A virus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. All subjects became infected with the challenge virus. By day 4, 16 (59%) developed middle ear pressures of -100 mm H2O or below and 4 (25%) of them developed OM. One subject (4%) developed purulent OM requiring myringotomy for pain relief. Middle ear effusion cultures were negative. PCR analysis of that subject's middle ear effusion and nasal washes were positive for influenza A virus and S. pneumoniae. These findings support a causal role for viral upper respiratory tract infections in the pathogenesis of OM, possibly mediated by middle ear underpressures and viral and bacterial middle ear infection.

Acute Disease↗

PubMed1995

Detection of Streptococcus pneumoniae in whole blood by PCR.

Streptococcus pneumoniae is a major cause of bacteremia in both children and adults. Currently, the diagnosis of pneumococcal bacteremia relies on the isolation and identification of the bacteria from blood cultures. We have developed a sensitive assay for the detection of S. pneumoniae in whole blood by the PCR. A specific primer-probe set (JM201 and JM202 primers with JM204 probe) designed from the penicillin-binding protein 2B gene was demonstrated to reproducibly detect between 10 and 100 fg of input purified S. pneumoniae DNA. This assay system was shown to be inclusive for all strains of S. pneumoniae evaluated, including 15 different serotypes and a battery of penicillin-resistant and -sensitive strains. The specificity of this PCR-based assay was demonstrated by its inability to support amplification from a series of human, bacterial, and yeast genomic DNAs. A general specimen preparation method which should be suitable for the purification of DNA from any pathogens in whole blood was developed. With this protocol it was possible to detect S. pneumoniae-specific DNA from whole blood specimens inoculated with as little as 4 CFU/ml. Copurified human blood DNA, ranging from 0 to 4.5 micrograms per PCR, did not affect the sensitivity of S. pneumoniae detection by PCR. A blinded clinical trial was used to compare the PCR-based assay with standard microbiological blood culture for the detection of S. pneumoniae bacteremia in 36 specimens obtained from pediatric patients seen in the emergency room of Children's Hospital of Pittsburgh. With culture as the "gold standard," the PCR-based assay had a sensitivity of 80% (4 of 5 culture-positive specimens were PCR positive) and a specificity of 84% (26 of 31 culture-negative specimens were PCR negative). However, three patients whose specimens were PCR positive and culture negative had histories suggestive of bacteremia, including recent positive blood cultures, treatment with antibiotics, cellulitis, and multiple emergency room visits for fever within a 24-h period. These data suggest that PCR-based assays for S. pneumoniae may prove useful to augment current methods of detection for S. pneumoniae bacteremia.

Bacteremia↗

PubMed1995

Adult respiratory papillomatosis: human papillomavirus type and viral coinfections as predictors of prognosis.

Pathologic material and the records of 29 patients with laryngeal papillomatosis were reviewed. The relationship between the type of human papillomavirus (HPV) and the presence of viral coinfections was correlated with clinical outcome. Using polymerase chain reaction, paraffin-embedded specimens were analyzed for the presence of HPV, Epstein-Barr virus (EBV), cytomegalovirus (CMV), and herpes simplex virus (HSV). The HPV type could be identified in 24 patients' specimens. Twenty-one patients were infected with HPV type 6. The other 3 were infected with HPV type 11 or 16. Three patients developed squamous cell carcinoma, of whom 2 had HPV type 11 or 16. We found HSV, EBV, and CMV in 50%, 12.5%, and 0% of specimens, respectively. An aggressive clinical course was observed in 17 patients. Evidence of coinfection with other viruses was identified in 11 (65%) of these patients. In contrast, a benign clinical course was observed in 7 patients, of whom 2 (29%) had viral coinfections. We conclude that the HPV type and the presence of viral coinfections may be predictive of an aggressive clinical course.

Adult↗

PubMed1994

Stenting or balloon angioplasty of stenosed autologous saphenous vein grafts in pigs.

In a model of early and aggressive vein graft stenosis in pigs, an intervention was performed with a single stent (n = 12 grafts), multiple stents (n = 6), or balloon angioplasty (n = 6), while grafts with mild stenoses were left untreated (n = 8). Four weeks after intervention, angiography showed that grafts with single stents, balloon angioplasty, or untreated grafts had patency rates of 92%, 83%, and 83%, respectively. Grafts receiving multiple stents, however, showed only a 17% patency rate (p < 0.05). Balloon dilatation or placement of a single stent improved the angiographic minimal diameter by 0.6 +/- 0.2 and 0.8 +/- 0.3 mm, respectively, over the short term, but this gain was lost during the follow-up period. Multiple stents showed a similar gain (0.5 +/- 0.2 mm) but more loss occurred during the follow-up period (2.4 +/- 0.2 mm). Histology revealed no significant differences between the treatment groups except for the prolonged presence of thrombus remnants in association with the stent wires. In conclusion, single stents and balloon angioplasty show good patency in early saphenous vein graft narrowing but multiple stents show a high occlusion rate.

Anastomosis, Surgical↗

PubMed1994

A gene for Crouzon craniofacial dysostosis maps to the long arm of chromosome 10.

Crouzon craniofacial dysostosis (CFD) is an autosomal dominant craniofacial disorder characterized by premature craniosynostosis, shallow orbits and hypoplastic maxilla. To map the gene responsible, we have used a mapping strategy of testing for linkage to known developmental genes. Analysis of a large kindred established linkage between CFD and three loci (D10S190, D10S209 and D10S216) that span a 13 cM region on chromosome 10q. A maximum pairwise lod score of 4.42 (theta = 0) at D10S190 was obtained and the addition of a second kindred produced a combined pairwise lod score of 5.32 (theta = 0) at the same locus. The developmental gene, PAX2, located within this region, is an attractive candidate gene.

Chromosome Mapping↗

PubMed1992

Meta-analysis of antibiotics for the treatment of otitis media with effusion.

OBJECTIVE: To reconcile conflicting reports of antibiotic efficacy for otitis media with effusion in children. DATA SOURCES: English-language MEDLINE search ("antibiotics" and "otitis" media with effusion") from January 1980 through December 1990. Current Contents 1990, consultation with experts, and references from review articles, textbook chapters, and retrieved reports. STUDY SELECTION: Randomized clinical trials with concurrent controls (placebo or no drug), and children with at least one ear not violated by tympanocentesis. Ten of the initial 82 articles were selected after blind review of the methods sections. DATA EXTRACTION: We independently evaluated each trial using 20 measures of internal and external validity, then extracted treatment and control responses for an end point of all affected ears free of effusion at the first posttreatment assessment. DATA SYNTHESIS: Pooled analysis of 1325 children yielded a rate difference of 22.8% (95% Cl, 10.5 to 35.1) that was minimally affected by interstudy quality differences, and was unlikely to represent publication bias. Variations in trial outcomes were not attributable to chance, study design, or choice of drug, but were inversely related to the control group natural cure rate. Children with chronic bilateral effusions not related to a recent episode of acute otitis media tended to have lower natural cure rates, and a more favorable response to therapy. CONCLUSIONS: Antibiotics have a clinically and statistically significant impact on the resolution of otitis media with effusion. The association between outcome and natural cure rate has important implications for the design and interpretation of future trials.

Anti-Bacterial Agents↗