Search PubMed⌕ Search

Biomedical subjects

J A Goldstein

Publications and source records attributed to J A Goldstein.

At least 37 records · Page 2Linked to original sources
PubMed2001

Identification and localization of five CYP2Cs in murine extrahepatic tissues and their metabolism of arachidonic acid to regio- and stereoselective products.

The CYP2C subfamily has been extensively studied in humans with respect to the metabolism of clinically important drugs, and polymorphisms have been identified in these enzymes. In the present study, a murine model was used to determine the possible physiological functions and extrahepatic distribution of CYP2Cs. Using the reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and immununohistochemistry, this report demonstrates that the mouse CYP2Cs are extensively distributed in extrahepatic tissues and localized to heart muscle, lung Clara and ciliated cells, kidney collecting ducts, the X-zone of female adrenals, reproductive organs, white blood cells, and eyes (in the optic nerve, rods, and cones). RT-PCR, subcloning, and sequencing of the products indicate that each CYP2C has a unique tissue distribution. Four cDNA fragments representing potentially new CYP2Cs were identified, each with its own organ-specific pattern of expression. Using a bacterial cDNA expression system, we found that recombinant proteins for each of the five full-length murine CYP2Cs metabolize arachidonic acid to different regio- and stereospecific products, including epoxyeicosatrienoic acids and hydroxyeicosatetraenoic acids. Regio- and stereospecific metabolites of arachidonic acid have been reported to affect important physiological functions such as inflammation, neutrophil activation, ion transport, cellular proliferation, and vascular tone. Our results suggest that the presence of CYP2C enzymes in heart muscle, aorta, kidney, lung, adrenals, eyes, and reproductive organs could regulate important physiological and/or pathological processes in these tissues.

Animals↗
PubMed2001

Identification of variants of CYP3A4 and characterization of their abilities to metabolize testosterone and chlorpyrifos.

CYP3A4 is the most abundant isoform of cytochrome P450 (CYP) in adult human liver. It metabolizes numerous clinically, physiologically, and toxicologically important compounds. The expression of CYP3A4 varies 40-fold in individual human livers, and metabolism of CYP3A4 substrates varies at least 10-fold in vivo. Single nucleotide polymorphisms (SNPs) in CYP3A4 were identified by direct sequencing of genomic DNA in 72 individuals from three different ethnic groups, including Caucasians, Blacks (African-Americans and African pygmies), and Asians. A total of 28 SNPs were identified, including five which produced coding changes M445T (CYP3A4*3), R162Q (CYP3A4*15), F189S (CYP3A4*17), L293P (CYP3A4*18), and P467S (CYP3A4*19). The latter four represent new alleic variants. Racial variability was observed for the frequency of individual SNPs. CYP3A R162Q was identified only in Black populations with an allelic frequency of 4%. CYP3A4 F189S and CYP3A4 M445T were identified in Caucasians with allelic frequencies 2% and 4%, respectively. L293P and P467S were only observed in Asians at allelic frequencies of 2%. The cDNAs for the F189S, L293P, M445T, and P467S mutant alleles were constructed by site-directed mutagenesis and expressed in an Escherichia coli expression system. Testosterone and the insecticide chlorpyrifos were used to assess the catalytic activities of the most common CYP3A4 allele (CYP3A4*1) and its allelic variants. CYP3A4 F189S exhibited lower turnover numbers for testosterone and chlorpyrifos, while CYP3A4 L293P had higher turnover numbers for both substrates. The turnover numbers of the CYP3A4 M445T and P467S alleles to metabolize these compounds were not significantly different from those of wild-type CYP3A4.

Alleles↗
PubMed2001

The use of bioresorbable material in craniofacial surgery.

It is clear that in just the short period of time that these products have been available significant technical advances continue to occur to make these materials easier to employ and use. Technical advances will continue to occur to make them more adaptable and strong for all forms of use in the craniomaxillofacial skeleton. The clinician also can envision them being employed as stable carriers to allow other factors to be brought into a wound-healing environment, such as growth factors or bone morphogenetic proteins. In addition, because the concepts behind bioresorbable fixation can continue to be extrapolated, the elimination of plates and screws with replacement with appropriate glues can be imagined. As long as the concepts of biocompatibility and immunogenicity are adhered to, the future seems without limitations for bioresorbable fixation products, and the author would urge strongly that plastic and reconstructive surgeons remain in the forefront of this movement.

Biocompatible Materials↗
PubMed2000

Human nonsyndromic hereditary deafness DFNA17 is due to a mutation in nonmuscle myosin MYH9.

The authors had previously mapped a new locus-DFNA17, for nonsyndromic hereditary hearing impairment-to chromosome 22q12.2-q13. 3. DFNA17 spans a 17- to 23-cM region, and MYH9, a nonmuscle-myosin heavy-chain gene, is located within the linked region. Because of the importance of myosins in hearing, MYH9 was tested as a candidate gene for DFNA17. Expression of MYH9 in the rat cochlea was confirmed using reverse transcriptase-PCR and immunohistochemistry. MYH9 was immunolocalized in the organ of Corti, the subcentral region of the spiral ligament, and the Reissner membrane. Sequence analysis of MYH9 in a family with DFNA17 identified, at nucleotide 2114, a G-->A transposition that cosegregated with the inherited autosomal dominant hearing impairment. This missense mutation changes codon 705 from an invariant arginine (R) to histidine (H), R705H, within a highly conserved SH1 linker region. Previous studies have shown that modification of amino acid residues within the SH1 helix causes dysfunction of the ATPase activity of the motor domain in myosin II. Both the precise role of MYH9 in the cochlea and the mechanism by which the R705H mutation leads to the DFNA17 phenotype (progressive hearing impairment and cochleosaccular degeneration) remain to be elucidated.

Amino Acid Sequence↗
PubMed2000

Multiple complex coronary plaques in patients with acute myocardial infarction.

BACKGROUND: Acute myocardial infarction is believed to be caused by rupture of an unstable coronary-artery plaque that appears as a single lesion on angiography. However, plaque instability might be caused by pathophysiologic processes, such as inflammation, that exert adverse effects throughout the coronary vasculature and that therefore result in multiple unstable lesions. METHODS: To document the presence of multiple unstable plaques in patients with acute myocardial infarction and determine their influence on outcome, we analyzed angiograms from 253 patients for complex coronary plaques characterized by thrombus, ulceration, plaque irregularity, and impaired flow. RESULTS: Single complex coronary plaques were identified in 153 patients (60.5 percent) and multiple complex plaques in the other 100 patients (39.5 percent). As compared with patients with single complex plaques, those with multiple complex plaques were less likely to undergo primary angioplasty (86.0 percent vs. 94.8 percent, P = 0.03) and more commonly required urgent bypass surgery (27.0 percent vs. 5.2 percent, P < or = 0.001). During the year after myocardial infarction, the presence of multiple complex plaques was associated with an increased incidence of recurrent acute coronary syndromes (19.0 percent vs. 2.6 percent, P < or = 0.001); repeated angioplasty (32.0 percent vs. 12.4 percent, P < or = 0.001), particularly of non-infarct-related lesions (17.0 percent vs. 4.6 percent, P < or = 0.001); and coronary-artery bypass graft surgery (35.0 percent vs. 11.1 percent, P < or = 0.001). CONCLUSIONS: Patients with acute myocardial infarction may harbor multiple complex coronary plaques that are associated with adverse clinical outcomes. Plaque instability may be due to a widespread process throughout the coronary vessels, which may have implications for the management of acute ischemic heart disease.

Aged↗
PubMed2000

Diagnostic and therapeutic approach to pancreatic cancer.

Adenocarcinoma of the pancreas ranks fourth as a cause of cancer death in adults in the United States and is the second most common cause of cancer deaths of all GI-related carcinomas. It usually presents late in its course. The clinical features are discussed, with emphasis on those that allow early detection of the disease, as well as a review of diagnostic methods and pre- and perioperative staging, which will allow the appropriate application of surgical and palliative therapeutic modalities. Despite the significant progress that has been made, further research studies are needed to advance our therapeutic approach to this aggressive cancer.

Biomarkers, Tumor↗
PubMed2000

The efficacy of bioresorbable fixation in the repair of mandibular fractures: an animal study.

PURPOSE: The efficacy of bioresorbable fixation has recently been described in the treatment of cranial vault deformities and in midfacial trauma. However, little to no data exist regarding its use in load-bearing areas. The purpose of this study is to analyze and compare the treatment of mandibular fractures by using a bioresorbable fixation system with a conventional titanium system in a canine model. MATERIALS AND METHODS: Four adult beagles constituted the experimental group (A), and 2 beagles constituted the control group (B). Both groups underwent extraoral iatrogenic left mandibular angle osteotomies/fractures and open reduction and internal fixation by use of a bioresorbable fixation system (A) or a titanium fixation system (B). All operated animals were allowed to function immediately. Lateral skull radiographs were obtained preoperatively, immediately postoperatively after reduction, and at 3- and 6-month intervals. Preoperative and 6-month follow-up bite registrations were taken. At the 3-month interval, 1 animal from the experimental group was killed, and at 6 months the remaining animals were killed for morphologic, radiographic, and histologic analysis of the fractured interface and screw sites. RESULTS: Morphologically, in the bioresorbable group, there was no clinical evidence of 1) intraoral/ extraoral incisional dehiscence of wound infection; 2) deviation of the occlusion from maximum intercuspation; 3) intraoral/extraoral palpability of the device; 4) mobility of the fractured segments on manual manipulation; or 5) malunion as visualized at the time of sacrifice. All bioresorbable plates were clinically absent after 6 months and associated with adequate fixation and healing. Adequate restoration of function was achieved in both groups, with all of the animals showing weight gain. Radiographically, good alignment of the inferior border was seen, and histologically bony union was apparent in all specimens. CONCLUSIONS: This bioresorbable fixation system is effective in the treatment of mandibular angle fractures in a dog model, despite being placed in a load-bearing region.

Absorbable Implants↗
PubMed2000

Solitary primary cutaneous CD30+ large cell lymphoma of natural killer cell phenotype bearing the t(2;5)(p23;q35) translocation and presenting in a child.

Primary cutaneous CD30+ large cell lymphoma is an unusual tumor most commonly seen in adults. Most of these lymphomas are of T-cell origin and carry a good prognosis. We present the case of a 4-year-old girl with stage IEA CD30+ large cell lymphoma with a CD56+ natural killer cell phenotype and the t(2;5)(p23;q35) translocation. After excision, the patient has been free of disease for 44 months. Primary cutaneous CD30+ large cell lymphoma is uncommon in children. To our knowledge, primary cutaneous CD30+ natural killer type lymphoma has not been reported previously. The indolent behavior of this tumor indicates its similarity to other primary cutaneous CD30+ large cell lymphomas and its difference from other CD56+ lymphomas involving the skin, which often exhibit an aggressive clinical course. Cases such as this one illustrate why the use of a single, or even a few, immunohistochemical stains can be misleading in regard to lymphoma classification and prognostication.

Antigens, Neoplasm↗
PubMed2000

Molecular pathogenesis in sporadic head and neck paraganglioma.

HYPOTHESIS: Similar to familial tumors, sporadic head and neck paragangliomas are associated with chromosomal deletions at either 11q13 or 11q22-23. BACKGROUND: Familial paragangliomas are inherited in an autosomal dominant pattern with genomic imprinting of the maternal allele. Genetic studies of familial paragangliomas have localized the causative genetic defect to two separate loci: 11q13.1 and 11q22-23. The molecular pathogenesis of sporadic head and neck paragangliomas has not been studied. METHODS: Blood and tumor samples from patients with sporadic head and neck paragangliomas were screened for deletions on chromosome 11 using DNA microsatellite markers and polymerase chain reaction. Polymerase chain reaction-amplified alleles from tumor specimens were compared with those from the blood of eight patients. A greater than 50% reduction in band intensity (as determined by densitometric analysis) between blood and tumor sample was indicative of a chromosomal deletion. RESULTS: Three of the eight patients were found to have deletions at chromosome 11q: two at chromosome 11q22-23 and one at 11q13. CONCLUSIONS: Sporadic head and neck paragangliomas are associated with deletions at chromosome 11q13 and 11q22-23. It is thus likely that sporadic and familial paragangliomas share a similar molecular pathogenesis.

Aged↗
PubMed2000

Comparison of the diameter consistency and dilating force of the controlled radial expansion balloon catheter to the conventional balloon dilators.

OBJECTIVES: Balloon dilation of a luminal narrowing is classically performed with a single-diameter balloon. A new multidiameter balloon that allows three progressively larger, controlled radial expansion diameters of a single-balloon catheter (controlled radial expansion, CRE) has been developed. The purpose of this study was to test the diameter consistency and dilating force at increasing pressure of the CRE balloon-dilating catheter and to compare these features with the conventional balloon-dilating catheters. METHODS: The CRE balloon catheter was compared with the Achiever, Eliminator, and Max Force using in vitro testing to determine their dilating diameters and dilating forces. RESULTS AND CONCLUSIONS: This in vitro study has shown that the new CRE balloon catheter with increasing diameter delivers consistently reproducible and progressively greater dilating force. This dilating force of the CRE balloon catheter at its third and maximum diameter inflation was similar to that of the Max Force TTS and significantly greater than that of the conventional balloon dilators, Eliminator and Achiever.

Catheterization↗
PubMed2000

CYP2C40, a unique arachidonic acid 16-hydroxylase, is the major CYP2C in murine intestinal tract.

We recently identified five different murine CYP2C cDNAs from a murine cDNA library. When expressed in a bacterial cDNA expression system, all five recombinant proteins metabolized arachidonic acid but produced distinctly different profiles. In addition, some CYP2C mRNAs were found in extrahepatic tissues, as well as in liver. Immunoblots with an antibody raised against recombinant CYP2C38, which recognizes all five murine CYP2Cs, demonstrated that among extrahepatic tissues, colon and cecum contained the highest amount of CYP2Cs. The highest concentration of CYP2Cs occurred in cecum and colon (cecum >/= proximal colon >> distal colon), with lower levels in duodenum, jejunum, and ileum. Immunohistochemical studies revealed that CYP2Cs were localized principally in epithelial cells and autonomic ganglia in gut and colon. Polymerase chain reaction amplification of reverse-transcribed mRNA using murine CYP2C-specific primers followed by cloning and sequencing identified CYP2C40 as the major CYP2C isoform expressed in murine intestinal tract. Recombinant CYP2C40 metabolized arachidonic acid in a regio- and stereospecific manner to 16(R)-HETE (hydroxyeicosatetraenoic acid) as the major product. To our knowledge, CYP2C40 is the first enzyme known to produce primarily 16-HETE. We conclude that CYP2C40 is one of the major cytochrome P450 proteins in the mouse intestinal tract. In the light of vasoactive and anti-neutrophilic effects of 16-HETE, we hypothesize that CYP2C40 may play an important role in endogenous biological functions in intestine.

Animals↗
PubMed2000

Bioresorbable fixation for congenital pediatric craniofacial surgery: a 2-year follow-up.

We describe our experience with the use of a polymeric biodegradable system for the correction of congenital pediatric craniofacial malformations. These fixation methods present several advantages over conventional metallic fixation systems. Our series consists of 51 patients that underwent craniofacial surgery, 46 for craniosynostosis, and 5 for encephalocele. The mean age of the patients was 3 years (median age 9 months). Patients with coronal or metopic craniosynostosis underwent a bifrontal craniotomy and anterior cranial vault and orbital reconstruction. Three patients with late sagittal synostosis underwent cranial vault reconstruction in two stages. Encephalocele defects were repaired with osteotomies, and/or onlay bone graft. Lactosorb (Lorenz Biomet, Warsaw, Ind.) plates (cut from a prefabricated mesh) and screws were employed using established fixation techniques. Cranial bone was the source of all bone graft when required. Pre- and postoperative clinical, radiographic and photographic examinations were performed on all patients. At 2 years follow-up, no evidence of infection, erythema, extrusion, instability of the bony fragments or relapse has been noted. The plates themselves were universally impalpable by the one year follow-up examination. The results in this series support the use of resorbable fixation systems in the correction of congenital craniofacial deformities.

Absorbable Implants↗
PubMed2000

Cloning of canine cytochrome P450 2E1 cDNA: identification and characterization of two variant alleles.

Cytochrome P450 (CYP) 2E1 is a toxicologically important enzyme that inactivates a number of drugs and xenobiotics and also bioactivates many xenobiotic substrates to their hepatotoxic or carcinogenic forms. Although cDNAs for the human, rodent, and rabbit forms of CYP2E1 have been isolated and studied extensively, there is an absence of information about canine CYP2E1, despite the fact that the dog is routinely used in drug safety studies. In this study, we isolated and sequenced a full-length CYP2E1 cDNA from a beagle liver cDNA library. The deduced canine CYP2E1 amino acid sequence exhibited 75 to 76% identity with rat, mouse, and rabbit CYP2E1 sequences, and 77% identity with human CYP2E1. Two populations of clones, differing at a single nucleotide, were isolated from the unamplified library. The T1453C base change results in a Tyr485His amino acid substitution, which is well beyond the heme binding region but is possibly part of a beta-sheet structure. An allele-specific polymerase chain reaction-based restriction enzyme test was developed for genotyping individual dogs from genomic DNA samples. One hundred mixed breed dogs were genotyped, and the frequencies of the Tyr485 and His485 alleles were found to be 0. 85 and 0.15, respectively. The canine Tyr485 and His485 alleles and human CYP2E1 were expressed in Escherichia coli cells, and catalytic activities of the proteins were assessed using the substrate chlorzoxazone. Although the two canine enzymes had similar catalytic activity; significant kinetic differences were seen between canine and human CYP2E1s.

Alleles↗
PubMed1999

Human CYP2C-mediated stereoselective phenytoin hydroxylation in Japanese: difference in chiral preference of CYP2C9 and CYP2C19.

Regio- and stereoselective hydroxylation of phenytoin was determined in liver microsomes of nine extensive (EM) and three poor metabolizers (PM) of mephenytoin. Hydroxyphenytoins (HPPH) were isolated and quantified after separation into four regio- and stereoisomers. The total rates of microsomal phenytoin 4'- hydroxylation were approximately 3-fold higher than those of 3'-hydroxylation, and not significantly different in EM and PM. Formation of 4'-(R)-HPPH was 4.4-fold higher in EM than in PM, whereas no clear differences between EM and PM were detected in the formation of 4'-(S)-, 3'-(R)-, and 3'-(S)-HPPH. Cytochrome P450 (CYP)2C9, expressed in a fission yeast, Schizosaccharomyces pombe, catalyzed the formation of 4'-(R)- and 4'-(S)-HPPH stereoselectively, as observed with EM, in which predominantly 4'-(S)-HPPH was formed. Recombinant CYP2C19 was more stereoselective for 4'-(R)-HPPH formation. These results, in addition to inhibition experiments with anti-human CYP2C antibody, indicate that phenytoin hydroxylation is mainly catalyzed by CYP2C9. Furthermore, CYP2C19 showed limited contribution to phenytoin 4'-hydroxylation with a different chiral preference from CYP2C9.

Antibodies↗
PubMed1999

Does spinal instrumentation influence the healing process of posterolateral spinal fusion? An in vivo animal model.

STUDY DESIGN: An in vivo sheep model was used to investigate the effect of spinal instrumentation on the healing process of posterolateral spinal fusion. OBJECTIVES: To examine the role of spinal instrumentation during the healing process of posterolateral fusion. SUMMARY OF BACKGROUND DATA: In long bone fractures, internal fixation improves the union rate but does not accelerate the healing process. Spinal instrumentation also improves the fusion rate in spinal arthrodesis. However, it remains unclear whether the use of spinal instrumentation expedites the healing process of spinal fusion. METHODS: Sixteen sheep underwent posterolateral spinal arthrodeses at L2-L3 and L4-L5 using equal amounts of autologous bone. One of those segments was selected randomly to be augmented with transpedicular screw fixation (Texas Scottish Rite Hospital spinal system). The animals were killed at 8 weeks or 16 weeks after surgery. Fusion status was evaluated by biomechanical testing, manual palpation, plain radiography, computed tomography, and histology. RESULTS: Instrumented fusion segments demonstrated significantly higher stiffness than did uninstrumented fusions at 8 weeks after surgery. Radiographic assessment and manual palpation showed that the use of spinal instrumentation improved the fusion rate at 8 weeks (47% versus 38% in radiographs, 86% versus 57% in manual palpation). Histologically, the instrumented fusions consisted of more woven bone than the uninstrumented fusions at 8 weeks after surgery. The 16-week-old fusion mass was diagnosed biomechanically, radiographically, and histologically as solid, regardless of pedicle screw augmentation. CONCLUSION: The current study's results demonstrated that spinal instrumentation creates a stable mechanical environment to enhance the early bone healing of spinal fusion.

Animals↗
PubMed1999

Gene structure of CYP2C8 and extrahepatic distribution of the human CYP2Cs.

Extrahepatic tissue distribution of the mRNAs for the four human CYP2Cs (2C8, 2C9, 2C18, and 2C19) was examined in kidney, testes, adrenal gland, prostate, brain, uterus, mammary gland, ovary, lung, and duodenum. CYP2C mRNAs were detected by RT-PCR using specific primers for each individual CYP2C. CYP2C8 mRNA was detected in the kidney, adrenal gland, brain, uterus, mammary gland, ovary, and duodenum. CYP2C9 mRNA was detected in the kidney, testes, adrenal gland, prostate, ovary, and duodenum. CYP2C18 mRNA was found only in the brain, uterus, mammary gland, kidney, and duodenum and CYP2C19 mRNA was found only in the duodenum. Immunoblot analysis of small intestinal microsomes detected both 2C9 and 2C19 proteins. In addition, genomic clones for CYP2C8 were sequenced, and long-distance PCR was performed to determine the complete gene structure. CYP2C8 spanned a 31 kb region. Comparative analysis of the 2.4 kb upstream region of CYP2C8 with CYP2C9 revealed two previously unidentified transcription factors sites, C/EBP and HPF-1, and the latter might be involved in hepatic expression. Although CYP2C8 has been shown to be phenobarbital inducible, neither a barbiturate-responsive regulatory sequence (a Barbie box) nor a phenobarbital-responsive enhancer module (PBREM) was found within the upstream region analyzed.

Aryl Hydrocarbon Hydroxylases↗