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S B Hunter

Publications and source records attributed to S B Hunter.

At least 37 records · Page 2Linked to original sources
PubMed1995

Reliability of differential PCR for the detection of EGFR and MDM2 gene amplification in DNA extracted from FFPE glioma tissue.

A series of 43 human gliomas, consisting of 30 glioblastomas, 7 anaplastic astrocytomas, 3 low grade astrocytomas, 2 ependymomas, and 1 oligodendroglioma, was studied for amplification of the epidermal growth factor receptor (EGFR) and mouse double minute 2 (MDM2) genes. DNA extracted from formalin-fixed, paraffin-embedded tissue sections was analyzed by differential PCR and the results were compared with slot blot examination of DNA extracted from frozen tissue from the same neoplasms. Twelve glioblastomas (40%) showed amplification of the EGFR gene, and overexpression of EGFR was evident in each of these tumors as indicated by the immunoperoxidase technique. Two of the tumors with EGFR gene amplification also revealed amplification of the MDM2 gene, while one additional glioblastoma revealed MDM2 amplification only. A 100% concordance in the detection of amplification was observed between differential PCR and slot blot analysis; consequently, these results indicate that differential PCR using DNA extracted from archival tissue sections is a reliable method of demonstrating gene amplifications in glial tumors.

Adult↗
PubMed1994

Comparison of ribotyping and multilocus enzyme electrophoresis for subtyping of Listeria monocytogenes isolates.

Ribotyping was compared with multilocus enzyme electrophoresis (MEE) for subtyping 305 Listeria monocytogenes isolates from clinical and nonclinical sources. For ribotyping, EcoRI-restricted genomic DNA fragments of L. monocytogenes strains were separated by agarose gel electrophoresis, and Southern blots were probed with a cloned Escherichia coli rrnB operon (plasmid pKK3535) labeled with digoxigenin. The L. monocytogenes isolates were divided into 28 distinct ribotypes, while MEE analysis divided the same isolates into 78 electrophoretic types (ETs). On the basis of their ribotype profiles, the strains were divided into two subgroups. The ribotype alpha (RT alpha) subgroup contained serotypes 1/2a, 1/2c, and 3a, and the ribotype beta (RT beta) subgroup contained serotypes 1/2b, 3b, 4b, and 4ab. This division is in complete agreement with MEE analysis, which divides the species into two subgroups (ET groups A and B), with the same serotype distribution in each subgroup. Overall, MEE was more discriminating than ribotyping. However, in several instances ribotyping discriminated between isolates within the same ET. Ribotyping was more discriminating for serotypes 1/2a, 1/2c, and 3a (Simpson's Index for Diversity [DI] = 0.81) than for serotypes 1/2b and 4b (DI = 0.76). A substantial proportion (69%) of serotype 1/2b and 4b strains clustered in five ETs and five ribotypes. These data suggest that ribotyping and MEE do not provide adequate discrimination between strains of serotypes 1/2b and 4b. Methods such as pulsed-field gel electrophoresis and random amplified polymorphic DNA analysis should be explored for further discrimination of strains of these serotypes.

Bacterial Typing Techniques↗
PubMed1994

Non-isotopic in situ hybridization method for mitochondria in oncocytes.

We used in situ hybridization to specifically identify mitochondria in a series of formalin-fixed, paraffin-embedded oncocytic lesions. Digoxigenin-labeled DNA probes were generated by the polymerase chain reaction (PCR), with primers designed to amplify a mitochondrion-specific 154 BP sequence within the ND4 coding region. Probes were hybridized with mitochondrial DNA under stringent conditions. Oncocytes were strongly and consistently stained, reflecting the high copy number of mitochondrial DNA within these cells. Because of the presence of endogenous biotin within mitochondria, digoxigenin is preferable to biotin as a label for detection of mitochondria.

Base Sequence↗
PubMed1994

Focal polypoid ischemia of the colon: atheroemboli presenting as a colonic polyp.

Cholesterol emboli are known to imitate a variety of disease processes, thereby leading to delayed diagnosis. We describe a patient with a localized polypoid mass of the colon without endoscopic evidence of generalized ischemic colitis. Histologic evaluation revealed this polyp to be the result of localized ischemia with identifiable submucosal atheroemboli. Localized polyp formation appears to be a rare manifestation of atheroemboli; consequently, focal ischemia, caused by atheroemboli, should be added to the differential diagnosis of polyps of the colon.

Colitis, Ischemic↗
PubMed1993

Polymerase chain reaction-based restriction fragment length polymorphism analysis of a fragment of the ribosomal operon from Rochalimaea species for subtyping.

Restriction endonuclease analysis of a polymerase chain reaction-amplified DNA fragment which included the spacer region between the genes coding for 16S and 23S rRNAs and a portion of the gene coding for 23S rRNA (spacer + 23S) was done on 10 previously characterized clinical isolates of Rochalimaea henselae, one clinical isolate of Rochalimaea quintana, and the type strains of R. henselae, R. quintana, Rochalimaea vinsonii, and Bartonella bacilliformis. Brucella abortus DNA was not amplified by the primer set used. The clinical isolates of Rochalimaea were obtained from blood or tissue from patients with and without preexisting disease. The amplicon from each strain was digested with five endonucleases (AluI, HaeIII, TaqI, HinfI, and MseI). AluI and HaeIII were useful in species differentiation and subtyping of R. henselae. R. henselae isolates showed six different restriction patterns with AluI and four patterns with HaeIII. TaqI, HinfI, and MseI were useful only in species differentiation. These observations indicate that PCR amplification of the spacer + 23S region of the ribosomal DNA of Rochalimaea spp., along with restriction endonuclease analysis, allows differentiation of Rochalimaea spp. from closely related genera, differentiation among the species within Rochalimaea, and differentiation of strains within R. henselae. The subtyping potential of this method may be useful for further clinical and epidemiologic studies of the spectrum of diseases caused by R. henselae.

Bacterial Typing Techniques↗
PubMed1993

Mutations in the p53 gene in human astrocytomas: detection by single-strand conformation polymorphism analysis and direct DNA sequencing.

The p53 gene was examined in a series of formalin-fixed paraffin-embedded astrocytic neoplasms of various types by polymerase chain reaction (PCR), single-strand conformation polymorphism analysis (SSCP), and direct sequencing of amplified DNA. PCR primers were designed to amplify three DNA fragments encompassing exons 5, 7, and 8 with splice sites, including all four mutational "hot spots" within this gene. SSCP was performed in a polyacrylamide gel containing 10% glycerol. Two mutations were found among the 20 high and intermediate grade adult astrocytomas studied by this sensitive screening technique and confirmed by sequencing of the PCR product. (1) An anaplastic astrocytoma disclosed a T-A transversion in Codon 246 giving rise to a methionine to lysine amino acid substitution. (2) A giant cell glioblastoma disclosed a G to A transition in Codon 285 resulting in a glutamic acid to lysine substitution. Both mutations were associated with loss of the normal allele. Twenty-three DNA fragments that disclosed no mutation by SSCP analysis were confirmed to be negative by direct sequencing of amplified DNA. No mutations were detected in a series of eight juvenile cerebellar astrocytomas, a biologically distinct form of low-grade astrocytoma. Mutations of the p53 gene may play an important pathogenetic role in a subset of human astrocytomas.

Adult↗
PubMed1992

Extraadrenal myelolipoma. A report of two cases.

Two cases of extraadrenal myelolipoma with unusual clinicopathologic features are described. The patient in case 1 had multifocal myelolipomas, involving both the lung and retroperitoneum, that mimicked malignancy, and the patient in case 2 had a single diffuse retroperitoneal myelolipoma without circumscription. Of possible etiologic significance is the fact that both patients were treated with exogenous steroids.

Aged↗
PubMed1992

Characterization of isolates of Mycobacterium avium serotypes 4 and 8 from patients with AIDS by multilocus enzyme electrophoresis.

Isolates of Mycobacterium avium serotypes 4 and 8 originating from patients with AIDS in New York City, Los Angeles, or San Francisco were further characterized by multilocus enzyme electrophoresis. Reference strains used to produce typing antisera were also examined. Thirty-one electrophoretic types (ETs) were found among 58 isolates of serotype 4, while 10 ETs were identified among 21 isolates of serotype 8. One major ET was found within each serotype, and these two ETs were closely related, separated by a genetic distance of only 0.05. Six ETs were found in more than one city. In four cases, isolates of serotypes 4 and 8 shared the same ET. Multilocus enzyme electrophoresis in combination with serotyping should be helpful in locating the specific infection sources of these commonly isolated opportunistic pathogens.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Meningococcal disease in the United States--1986. Meningococcal Disease Study Group.

Active surveillance for invasive meningococcal disease was conducted during 1986 and 1987 in six areas of the United States with a total population of approximately 34 million persons. The incidence of meningococcal disease was 1.3:10(5). The highest incidence of disease among the surveillance areas was in Los Angeles County (1.65:10(5). Neisseria meningitidis serogroups B and C caused about equal amounts of disease, which reflects a recent increase in the incidence of group C disease. Group C caused more than half of the cases of meningococcal disease in Los Angeles and Tennessee but less than one-third of the cases in Missouri and Oklahoma. Multilocus enzyme electrophoresis demonstrated that a group of closely related isolates of N. meningitidis was prevalent in Los Angeles during the surveillance period and was associated with an increased incidence of meningococcal disease there.

Adolescent↗
PubMed1991

Restriction fragment length polymorphisms in rRNA operons for subtyping Shigella sonnei.

Shigella sonnei is the most frequent cause of shigellosis in the United States. Epidemiologic studies of this organism have been hampered by the lack of adequate typing procedures. Ribosomal DNA analysis (ribotyping), a method which analyzes restriction fragment length polymorphisms in the chromosomal genes that encode rRNA, has recently been shown to be useful for microbial species identification and subtyping. To determine whether ribotyping could be used to distinguish between S. sonnei isolates, we conducted Southern hybridization studies on isolates from 16 different geographic locations and from four recent outbreaks. S. sonnei genomic DNA fragments generated following digestion with SalI hybridized with Escherichia coli 16S and 23S rRNAs to produce six distinct patterns; strains with patterns 1, 2, and 3 were each further subdivided into two additional patterns by using PvuII, SmaI, and SstI, respectively. Epidemiologically related strains had identical patterns. Ribotyping appears to be a useful tool for epidemiologic studies of shigellosis caused by S. sonnei.

Bacterial Typing Techniques↗
PubMed1989

Potential risks in retrovenous revascularization of the myocardium.

Retrovenous perfusion of the myocardium via the coronary sinus and cardiac veins was one of the earliest attempted forms of myocardial revascularization. Although coronary artery revascularization has almost completely replaced venous revascularization as the procedure of choice, the latter approach is still occasionally performed. We present two cases of hemorrhage within viable and nonviable myocardium noted at autopsy in patients who had undergone retrovenous revascularization hours before death. The two cases illustrate a complication of this procedure that has not previously been emphasized.

Aged↗
PubMed1988

Two-site monoclonal antibody quantitative ELISA for toxic shock syndrome toxin-1.

A two-site monoclonal antibody (MAB) quantitative enzyme-linked immunosorbent assay (ELISA) was developed that enables quantitation of toxic shock syndrome toxin-1 (TSST-1) down to 0.25 ng/ml and detection of TSST-1 to 0.06 ng/ml. Interference by Staphylococcus protein A was eliminated by incorporating normal rabbit serum into the test sample diluent. In the process of selecting an MAB pair for a two-site 'sandwich'-type ELISA, the MABs were screened for inhibition or common epitope binding. Some MABs that reacted with antigen that was adsorbed to a polystyrene well would not bind to antigen that was presented in a more natural configuration, as in the case of antigen immobilized by trapping antibody. Conversely, MABs that reacted with antigen that was immobilized by another antibody did not all function as trapping antibodies when adsorbed directly to a polystyrene surface. ELISAs that used polyclonal antibodies in the capture mode and MAB conjugate as the second antibody were generally more sensitive than were those that used polyclonal antibodies for both capture and indicator functions. MAB screening and selection schemes should be carefully designed to evaluate MABs in the mode in which they will be used in the final assay.

Animals↗
PubMed1987

Multiple sclerosis mimicking primary brain tumor.

Surgical biopsy specimens of multiple sclerosis plaques have been only infrequently reported, and the scanty descriptions of these specimens have generally emphasized the inflammatory nature of the lesion. We present surgical specimens from four patients with multiple sclerosis on whom biopsies were performed because of clinical features mimicking brain tumor. Both general pathologists and neuropathologists involved with these cases experienced difficulty in arriving at the correct diagnosis. In all four cases, the lesions were remarkably uniform in microscopic appearance, consisting of monotonous sheets of gemistocytic astroglia interspersed by numerous foamy macrophages. In sections stained with hematoxylin-eosin, the most helpful diagnostic features were the even distribution of the foamy macrophages and the absence of associated necrosis. In each case, the diagnosis was confirmed with special stains that disclosed total destruction of myelin sheaths with relative preservation of axons. Significant inflammatory infiltration was present in only one of five biopsy specimens.

Adult↗
PubMed1986

Enzyme-linked immunosorbent assay with major outer membrane proteins of Brucella melitensis to measure immune response to Brucella species.

We developed an enzyme-linked immunosorbent assay (ELISA) system to measure human immunoglobulin G (IgG) and IgM response to the major outer membrane proteins of Brucella melitensis. The ELISA was more sensitive in detecting antibody than a standard microagglutination (MA) test with B. abortus antigen. Of 101 sera from persons with suspected brucellosis, 79 (78.2%) gave ELISA IgM titers greater than or equal to the B. abortus MA titer without 2-mercaptoethanol (2ME), which measures both IgM and IgG. Of the 101 sera, 97% gave ELISA IgG titers greater than or equal to the MA with 2ME titer. A total of 58 sera, drawn from 11 human patients from 1 to 29 weeks after onset of brucellosis, gave higher geometric mean titers for the ELISA IgG test than for the MA with 2ME test. These 58 sera also gave ELISA IgM geometric mean titers that were greater than or within one doubling dilution of the geometric mean titers of MA without 2ME. In addition to detecting antibody response to B. abortus, B. melitensis, and B. suis, the ELISA was sensitive to antibody response to human and canine infections with B. canis. The B. canis antibody response is not detected by the MA test with B. abortus antigen. The ELISA, with a standard preparation of major outer membrane proteins of B. melitensis as antigen, appears to be useful in measuring antibody response in humans to infections by all species of Brucella known to infect humans.

Agglutination Tests↗
PubMed1985

Auditory brain-stem potentials with unilateral pontine hemorrhage.

Although there have been extensive anatomical and physiological studies in animals, the actual neural sources, or even the laterality, of some components of auditory brain-stem evoked potentials in humans are uncertain. We studied these responses in a 56-year-old patient who had a clearly demarcated pontine hemorrhage on the right side. The patient was somnolent, with dense left hemiplegia and signs of involvement of right cranial nerves V, VI, and VII. Stimulation of the left ear (ie, contralateral to the lesion) evoked a normal series of waves with clearly resolved positive components peaking at 2.0, 3.3, 4.8 (wave IV), and 6.0 ms (wave V). Stimulation of the right ear (ie, ipsilateral to the lesion) evoked only waves I, III, and IV. These results suggest that a pathway ipsilateral to the stimulated ear is necessary and sufficient for generation of auditory wave V and that wave IV is generated in bilateral pathways.

Cerebral Hemorrhage↗