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Biomedical subjects

T L Johnson

Publications and source records attributed to T L Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1991

HPV detection by polymerase chain reaction (PCR) in verrucous lesions of the upper aerodigestive tract.

Nineteen formalin-fixed, paraffin-embedded verrucous lesions of the upper aerodigestive tract (UADT) were evaluated for the presence of human papillomavirus (HPV) 6b/11, 16, and 18 DNA sequences using the polymerase chain reaction (PCR), in-situ hybridization, and dot blot analysis. HPV DNA was confirmed in two dysplastic papillomas only; both cases contained HPV 6b/11. E6-E7 portions of HPV DNA was not reproducibly detected in any of the 11 verrucous carcinomas, 4 verrucous hyperplasias, or 2 mature papillomas. In-situ hybridization and dot blot analysis confirmed HPV 6b/11 in the two dysplastic papillomas and failed to identify HPV in the other verrucous lesions.

Adult↗
PubMed1991

Lymphangioma circumscriptum of the vulva. A report of two cases.

Lymphangioma circumscriptum is an uncommon dermatologic problem that only rarely affects the vulva. It is considered to be a circumscribed developmental defect of lymphatic tissue in the dermis. We encountered two patients whose clinical manifestations required management with extensive vulvar surgery. These cases illustrate the spectrum of presentation of this disorder and its treatment.

Adult↗
PubMed1991

Skeletal muscle following tonic overload: functional and structural analysis.

Functional overloading of skeletal muscle induces a compensatory hypertrophy as an adaptive response to increased functional demand. Overload of the extensor digitorum longus (EDL) muscle (129 ReJ strain male mouse) was induced by unilateral surgical removal of a synergistic muscle, tibialis anterior (TA). Response of the EDL to overload for 7, 21, and 42 d was analyzed for changes in 1) muscle weight, 2) myofiber type distribution, 3) myofiber cross-sectional area by fiber type, 4) speed of contraction and relaxation of the muscle, 5) force of contraction, and 6) myofiber morphologic integrity. The weight of the EDL significantly increased. The overload caused no impairment of muscle contractility and did not have a significant effect on isometric twitch contraction time to peak tension or the time to one-half relaxation of the twitch. Overloaded muscles demonstrated a transient shift in fiber type profile with preferential hypertrophy of Type IIA fibers that occurred in the early phase of overload while type IIB fibers were recruited by 42 d. No significant increase in myofiber number in overloaded muscles occurred. Some morphologic changes in over-loaded muscles parallel those found in patients with neurogenic muscular disorders. However, overloaded muscle did not exhibit a significant occurrence of fiber branching from controls in the midbelly region of the muscle.

Adaptation, Physiological↗
PubMed1991

Transfer and expression of a Streptomyces cholesterol oxidase gene in Streptococcus thermophilus.

The recombinant plasmid pNCO937 (8.1 kbp) containing a Streptomyces sp. cholesterol oxidase gene was introduced into Streptococcus thermophilus by electrotransformation. Transformation frequency was 7.2 x 10(5) colony forming units/micrograms of DNA. The presence of the cholesterol oxidase gene in S. thermophilus was confirmed with Southern blot analysis using a biotinylated probe. Thin-layer chromatographic analysis showed the expression of the Streptomyces cholesterol oxidase gene resulting in the oxidation of cholesterol to 4-cholesten-3-one. S. thermophilus may be a suitable host for the expression of other genes regulating prokaryotic cholesterol metabolism.

Animals↗
PubMed1990

Cloning and expression of peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase F in Escherichia coli.

The peptide-N4-(N-acetyl-beta-D-glucosaminyl) asparagine amidase F (PNGase F) gene from Flavobacterium meningosepticum was cloned into a high copy number Escherichia coli plasmid. Levels of PNGase F activity produced in cultures of the recombinant strain were up to 100-fold higher than those obtained in cultures of F. meningosepticum. The complete PNGase F gene sequence was determined. Comparison of the predicted amino acid sequence of pre-PNGase F to the N-terminal sequence of the native mature enzyme indicates that the protein is synthesized with a 40-amino acid signal sequence that is removed during secretion in F. meningosepticum. The recombinant PNGase F produced in E. coli is a mixture of products comprised predominantly of two proteins with molecular masses of 36.3 and 36.6 kDa. These proteins have a higher apparent molecular mass than the 34.7-kDa native enzyme. N-terminal amino acid sequencing demonstrated that these higher molecular mass products result from cleavage of the pre-PNGase F in E. coli upstream of the native N terminus. The PNGase F gene was engineered to encode a preenzyme that was processed in E. coli to give an N terminus identical to that of the native enzyme. Purified preparations of this form of recombinant PNGase F were shown to be suitable for glycoprotein analyses since they possess no detectable endo-beta-N-acetylglucosaminidase F, exoglycosidase, or protease activity.

Amidohydrolases↗
PubMed1990

ABC-immunoperoxidase staining of cytologic preparations: improvement of specificity.

Immunoperoxidase (IP) methods perfected on formalin-fixed, paraffin-embedded tissues (FFPE) and then applied to aspirate smears may result in high background staining and a significant number of false-positive results. This is especially true if polyclonal primary antibodies are used or if aspirates and fluids contain a high interstitial or serum protein content. Because of a recurring problem with antiserum to alpha-fetoprotein (AFP), AFP was selected as the primary test antibody with which to evaluate our avidin-biotin complex (ABC)-IP method. The same method, with diaminobenzidine (DAB) or aminoethylcarbazole (AEC) chromogens, was performed on six types of cytologic preparations of a fresh liver specimen. The liver did not stain for AFP in FFPE and frozen tissue; therefore, it could be used to evaluate potential false-positive staining of direct touch imprints, washed aspirate smears, and cytospins that were both air-dried and alcohol-carbowax-fixed. Initial chromogen incubation times were standardized to give identical results on AFP-positive fixed hepatoma and fetal liver controls. Cytologic preparations immunostained with ABC-IP with AEC chromogen resulted in varying background and hepatocyte staining. In comparison, the ABC-IP method using DAB chromogen resulted in no false-positive results and a clean background. The ABC-IP method with AEC standardized for sensitivity on a fixed tissue control required a markedly shortened chromogen incubation time to preclude significant false-positive staining of cytology specimens. It appears that use of AEC chromogen for this antibody with incubation time standardized on a FFPE tissue control and then applied to cytologic preparations also amplifies nonspecific and background staining, contributing difficulty in assessing a true-positive result.(ABSTRACT TRUNCATED AT 250 WORDS)

Avidin↗
PubMed1990

Normal human colon cells suppress malignancy when fused with colon cancer cells.

Normal human colon mucosa cells and cells obtained from histologically normal tissues near that cancer were fused with human colon cancer cells. Resultant hybrid populations of normal and malignant cell fusions behaved as nonmalignant cells in culture, were unable to grow in soft agar, did not express tumor-associated antigens, and were nontumorigenic in nude mice. Autofusion of the cancer cell population led to a phenotype intermediate between normal and malignant cells. That is, the cultures had a much lower plating efficiency in soft agar, and the tumors had a longer latency and slower growth rate in nude mice. This is the first cell culture system to demonstrate that normal epithelial cells can suppress malignancy of their autologous cancer cells, and is a prelude to more extensive studies of genetic events involved in malignant conversion of human colonic epithelium.

Animals↗
PubMed1989

Characterization of the dermatan sulfate proteoglycans, DS-PGI and DS-PGII, from bovine articular cartilage and skin isolated by octyl-sepharose chromatography.

Two forms of dermatan sulfate proteoglycans, called DS-PGI and DS-PGII, have been isolated from both bovine fetal skin and calf articular cartilage and characterized. The proteoglycans were isolated using either (a) molecular sieve chromatography under conditions where DS-PGI selectively self-associates or (b) chromatography on octyl-Sepharose, which separates DS-PGI from DS-PGII based on differences in the hydrophobic properties of their core proteins. The NH2-terminal amino acid sequence of DS-PGI from skin and cartilage is identical. The NH2-terminal amino acid sequence of DS-PGII from skin and cartilage is identical. However, the amino acid sequence data and tryptic peptide maps demonstrate that the core proteins of DS-PGI and DS-PGII differ in primary structure. In DS-PGI from bovine fetal skin, 81-84% of the glycosaminoglycan was composed of IdoA-GalNAc(SO4) disaccharide repeating units. In DS-PGI from calf articular cartilage, only 25-29% of the glycosaminoglycan was composed of IdoA-GalNAc(SO4). In DS-PGII from bovine fetal skin, 85-93% of the glycosaminoglycan was IdoA-GalNAc(SO4), whereas in DS-PGII from calf articular cartilage, only 40-44% of the glycosaminoglycan was IdoA-GalNAc(SO4). Thus, analogous proteoglycans from two different tissues, such as DS-PGI from skin and cartilage, possess a core protein with the same primary structure, yet contain glycosaminoglycan chains which differ greatly in iduronic acid content. These differences in the composition of the glycosaminoglycan chains must be determined by tissue-specific mechanisms which regulate the degree of epimerization of GlcA-GalNAc(SO4) into IdoA-GalNAc(SO4) and not by the primary structure of the core protein.

Amino Acid Sequence↗
PubMed1989

The significance of atypical apocrine cells in fine-needle aspirates of the breast.

Apocrine metaplastic cells are frequently present in fine-needle aspirates (FNAs) of breast lesions, especially fibrocystic disease. Occasionally, apocrine cells may be atypical and present diagnostic difficulties. The morphologic features of six breast FNAs that contained atypical apocrine cells in breast aspirates. In the six abnormal cases, the large, pleomorphic, atypical apocrine cells were the predominant cell type and occurred singly and in syncytial tissue fragments. The cells had large, eccentric, vesicular nuclei and usually multiple macronucleoli. The histologic diagnoses in the cases were apocrine carcinoma (five cases) and atypical apocrine metaplasia (one case). In comparison, benign apocrine cells are relatively small and uniform and arranged in cohesive, orderly sheets. It is concluded that, in breast FNAs, the predominance of atypical apocrine cells, occurring singly and in syncytia, should raise the suspicion of carcinoma.

Aged↗
PubMed1989

Attention to auditory and peripheral visual stimuli: effects of arousal and predictability.

Changes in the distribution of attention among auditory and peripheral visual stimuli were examined in a choice reaction time paradigm. Two variables were manipulated: predictability of stimulus locations and arousal state of subjects. The arousal level of some subjects was raised by occasionally exposing them to brief, mild electric shocks. On most trials either a tone or a light was presented alone (single-stimulus trials). However, on 20% of the trials both a tone and light were presented simultaneously (dual trials). Two dependent variables were used to assess dominance of attention: reaction time (on all trials) and percentage of time each modality was chosen on dual trials. Neither modality was dominant when subjects were in a nonaroused state and stimulus locations were unpredictable. However, peripheral vision dominated when stimulus locations were predictable or when the subjects' level of arousal was raised. The results are discussed with reference to previous research on sensory dominance and on the facilitating or inhibiting effects of auditory stimuli on reaction time.

Adolescent↗
PubMed1989

Clinicopathologic features of ovarian mixed mesodermal tumors and carcinosarcomas.

Over a 27-year period there were 15 patients treated at the University of Michigan Medical center for carcinosarcomas or mixed mesodermal tumors of the ovary. Overall median survival was 11 months. Median survival was 4 months in patients with carcinosarcomas and 13 months in patients with mixed mesodermal tumors (P = 0.066). Patients with a chondrosarcomatous element had a significantly longer median survival than patients with mixed mesodermal tumors lacking cartilaginous differentiation (P = 0.031). The presence of a rhabdomyosarcomatous element did not affect survival. The size of the primary tumor, presence of ascites, FIGO stage, and degree of initial resection (optimal versus suboptimal) did not affect survival. There was no difference in survival between patients receiving postoperative chemotherapy and patients undergoing postoperative irradiation.

Adult↗
PubMed1988

Proteoglycans of bovine articular cartilage. Studies of the direct interaction of link protein with hyaluronate in the absence of proteoglycan monomer.

When link protein binds to hyaluronate in the absence of proteoglycan monomer a high molecular weight complex is formed. Two assay procedures have been developed to examine the formation of the complex and the rate and stoichiometry of binding of link protein to hyaluronate in the complex. In the first, the complex is isolated by differential centrifugation, and the stoichiometry of binding of link protein to hyaluronate in the sedimented complex is determined. In the second assay, which involves turbidimetry, the rate of complex formation (delta A420/min) is determined, and the amount of complex formed is determined in terms of the maximum turbidity (A420,max) attained. The effects of temperature, pH, initial total solute concentration, and the ratio by weight of link protein to hyaluronate on the amount of complex formed and on the rate of complex formation were examined. There is a linear correlation between the amount of complex formed as determined by turbidity and by differential centrifugation. Using these assays, we examined the specificity of the binding of link protein to hyaluronate and the capacity of hyaluronate oligosaccharides to competitively inhibit the binding of link protein to hyaluronate. Hyaluronate decasaccharide is the oligosaccharide of minimum size that strongly inhibits the binding of link protein to hyaluronate. Proteoglycan monomers dissociate from hyaluronate as the pH is decreased from pH 7 to pH 5. Turbidimetric studies show that the rate of binding of link protein to hyaluronate increases with decreasing pH. The binding affinity of proteoglycan monomers for hyaluronate is decreased at pH 5, whereas the binding affinity of link protein for hyaluronate is not. This difference in the effect of pH on the stability of binding of link protein to hyaluronate, compared with proteoglycan monomer, explains in part the capacity of link protein to stabilize the binding of proteoglycan monomer to hyaluronate at pH 5.

Animals↗
PubMed1988

Prognostic implications of the tall cell variant of papillary thyroid carcinoma.

The tall cell variant (TCV) of papillary thyroid carcinoma, characterized by a population of tall columnar cells with a height at least twice the width, was analyzed in 12 patients and compared to tumors from 12 patients with the usual type of papillary thyroid carcinoma (UPTC) matched for age, sex, and date of diagnosis to determine if tall cell histology had prognostic significance. Patients with TCV had significantly higher incidences of extrathyroidal disease, recurrent disease, and metastases compared to patients with UPTC. TCV patients also died of their tumors more frequently than UPTC patients (3/12 versus 0/12). There was no significant difference in tumor size or in the incidence of cervical lymph node involvement between the patient groups. These results show that TCV of papillary thyroid carcinoma has a more aggressive clinical course and a worse prognosis than UPTC in patient groups with similar age and sex distribution, length of follow-up, and tumor size.

Adult↗
PubMed1988

Candida hepatitis. Histopathologic diagnosis.

Candida hepatitis, usually a manifestation of disseminated candidiasis in immunocompromised patients, is difficult to diagnose antemortem. We studied six patients with proven hepatic candidiasis to assess features helpful in deriving a correct diagnosis. Five patients were immunosuppressed as a result for treatment for leukemia; one was immunosuppressed due to renal transplantation. All had sustained fevers greater than 101 degrees F, elevated alkaline phosphatase levels, and multiple hepatic and splenic defects--presumably abscesses--on abdominal CT scan. Twelve liver biopsies (nine needle, three wedge) were examined. Biopsies from four patients contained identifiable Candida organisms within suppurative granulomas; a biopsy from a fifth patient grew Candida albicans in cultures. In the sixth patient, the first biopsy was culture positive for Candida albicans, and the second biopsy, a fine-needle aspirate, contained Candida organisms and purulent material. In all of the nondiagnostic biopsies, as well as in regions of the diagnostic biopsies around the suppurative granulomas, mass-associated obstructive changes were noted. These included pericentral sinusoidal dilatation and cholestatic inflammation characterized by periportal ductular proliferation with surrounding neutrophils and edema. We conclude that in the appropriate clinical setting, these mass-associated histologic findings are suggestive of adjacent Candida abscesses. Definite diagnosis requires either the identification of Candida organisms within inflammatory hepatic lesions or positive culture of Candida from the liver biopsy.

Adolescent↗
PubMed1988

Paragangliomas of the head and neck: immunohistochemical neuroendocrine and intermediate filament typing.

Twenty-nine paragangliomas of the head and neck region including 20 glomus jugulare (GJ) and nine carotid body (CB) tumors were evaluated for the presence of neuroendocrine and intermediate filament antigens. Immunohistochemistry on formalin-fixed, paraffin-embedded tissue was used to identify: S-100 protein (S-100); neuron-specific enolase (NSE); chromogranin A (CHA); serotonin (SER); synaptophysin (SYN); cytokeratin (CK); neurofilament (NF); desmin (DES); vimentin (VIM); and glial fibrillary acidic protein (GFAP). S-100 protein staining of sustentacular cell nuclei and cytoplasm was found in all tumors and was present in chief cells in 4 of 20 GJ and 3 of 9 CB tumors. All tumors stained with at least three neuroendocrine markers (29 of 29 NSE, 28 of 29 SYN, 26 of 29 CHA, 25 of 29 SER). CK was detected in 2 GJ and 1 CB tumor using anticytokeratins AE 1/3 and CAM 5.2. Neurofilament protein could not be demonstrated in fixed material, and all tumors were negative for GFAP and desmin. Vimentin was inconsistently detected in chief and sustentacular cells. We conclude that, in formalin-fixed material, paragangliomas have S-100 protein staining of sustentacular cells with chief cells containing antigens associated with neuroendocrine differentiation. The presence of CK in some paragangliomas is consistent with recent tissue culture studies demonstrating immunoblot confirmation of CK in pheochromocytomas and represents a potential source of immunohistologic misinterpretation in diagnosis, unless a panel of markers is utilized.

Antibodies↗
PubMed1987

Hurthle cell thyroid tumors. An immunohistochemical study.

Twenty-three Hurthle cell neoplasms of the thyroid were analyzed immunohistochemically for thyroglobulin, carcinoembryonic antigen (CEA), and for immunoreactivity with a monoclonal antibody to p21 ras oncogene product. Both benign and malignant tumors defined by the presence or absence of invasion and metastasis stained positively for thyroglobulin. Most tumors expressed both CEA and p21 ras oncogene product. Clinicopathologic analysis showed that malignant tumors were larger, occurred in slightly older patients (mean age, 52.8 years), and had an almost equal sex distribution, whereas benign tumors were more common in women and occurred in younger patients (mean age, 44.7 years). These results indicate that both benign and malignant Hurthle cell thyroid tumors produce thyroglobulin and express both CEA and p21 ras oncogene product, whereas adjacent normal thyroid tissues showed weak to absent immunoreactivity for p21 ras oncogene product. Because there are no specific immunohistochemical markers to distinguish between benign and malignant Hurthle cell tumors, one needs to rely on traditional histologic features such as invasion and metastasis to distinguish between benign and malignant Hurthle cell neoplasms.

Adult↗