Biomedical subjects
Publications and source records attributed to L Cheng.
Previous studies do not agree on relationships between cleft palate and the cranial base. This study comparing normal and cleft lip-and-palate samples finds no significant difference in cranial base angle, but significantly shorter clivus length in the cleft sample.
Isolation of Mycoplasma pneumoniae was accomplished in gingival biopsies of four patients exhibiting chronic inflammatory periodontal disease using in situ hybridization with biotin-labeled DNA probes. The distribution of the M. pneumoniae organisms was mainly cytoplasmic and evenly spread around the nuclei of connective tissue cells. Controls of nondisease sites in the same patients showed no infection with M. pneumoniae. Since M. pneumoniae is the only Mycoplasma known to be pathogenic, their role in the pathogenesis of periodontal disease needs further study.
An immunohistochemical technique using a commercially available monoclonal antibody to the estrogen receptor in formalin-fixed breast tumors is described. The author's technique is compared to three other recently published techniques in 27 case studies. The authors' method using pronase enzyme pretreatment and alkaline phosphatase as the third antibody yielded the best results. Comparison with the standard dextran-coated charcoal cytosolic assay results from the cases selected yielded a 100% sensitivity and 89% specificity for the authors' technique. The advantages of the immunohistochemical method over the biochemical assay are discussed and clinical implications are suggested. A step-by-step procedure for the authors' technique follows the text.
Murine monoclonal antibodies were used to identify tumor-cell membrane antigens on a new human mesothelioma cell line. Hybridomas were constructed by fusing SP2/0 mouse myeloma cells with spleen cells from Balb/C mice immunized by the human mesothelioma cell line MT-1. Hybridoma antibody was detected in 55/672 microculture wells that reacted to these MT-1 tumor cells by an indirect 125I-protein A binding assay. Six cultures produced antibody binding selectively to the MT-1 tumor cells but not to a human lymphoblastoid cell line. These six hybridomas were cloned: three were IgG and three were IgM antibodies. One monoclonal, MAb 45, reacted with 4 of 7 human mesothelioma cell lines but with only 1 of 11 carcinomas, 1 of 3 sarcomas, 4 of 11 melanomas, and 0 of 5 lymphoid lines. The other five monoclonals had a much broader cross-reactivity. Using an immunoperoxidase technique, MAb 45 bound to mixed-type malignant mesotheliomas but not to normal lung and pleura. The specificity of MAb 45 for diffuse mesotheliomas and the low cross-reactivity with carcinomas and normal adjacent tissues suggest that this monoclonal may be clinically useful.
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Rapid detection of cytomegalovirus (CMV) from pulmonary specimens in immunosuppressed persons may provide an origin for pneumonia. In situ DNA hybridization has been effective for detection of CMV in otherwise nondiagnostic histologic material. Studies comparing bronchoalveolar lavage (BAL) with open-lung biopsy have shown the former to be superior in detecting most pulmonary pathogens affecting immunocompromised patients. Fifty consecutive BAL specimens were studied to compare direct in situ DNA hybridization, routine tissue culture, and conventional cytologic examination to assess the efficacy of the hybridization technic to rapidly detect CMV. Using tissue culture as the standard, a sensitivity of 90% (28 of 31) and specificity of 63% (12 of 19) were observed with the CMV probe. Discrepant results between the probe and tissue culture were present in ten cases. There were seven probe-positive, culture-negative cases, three of which had systemic CMV infection, including two patients with inclusions noted by conventional cytologic examination. Three probe-negative, culture-positive cases were found. In the authors' laboratory, the predictive value of a positive CMV probe is 80% (28 of 35). In contrast to the probe, conventional cytologic examination revealed CMV inclusions in only 23% (7 of 31) of the culture-positive cases. An average of 21 days was required for CMV cultures to become positive; probe results were available within 24 hours. The authors conclude direct in situ DNA hybridization is a useful rapid method for the detection of CMV in BAL specimens submitted for cytologic examination.
Rabbit antibodies to bovine S-100 protein were tested by immunoperoxidase technics against fresh hairy cell leukemia (HCL) cells obtained from nine patients (peripheral blood in six and spleen in three), as well as lymphoblastoid cell lines derived from three patients with HCL. Peripheral mononuclear cells from three normal persons and two patients with chronic lymphocytic leukemia (CLL) and cells from two melanoma lines were used as controls. The melanoma cell lines, cell lines derived from patients with HCL, and fresh HCL cells displayed cytoplasmic and nuclear positivity after exposure to anti-S-100 protein sera. By contrast, normal peripheral blood lymphocytes and CLL cells were negative for S-100 protein. Additional studies were performed by immunoperoxidase technics on representative sections of formalin-fixed splenic tissues from eight patients who had splenectomies. The cause of splenectomy was HCL in three, traumatic rupture in one, CLL in one, Hodgkin's disease in one, and hypersplenism in two patients. Sections from all three HCL patients showed moderate to marked positivity with antisera to S-100 protein. These results strongly suggest the presence of S-100 protein in HCL cells.
The streptozotocin-induced diabetic rat was used to test the hypothesis that Na+-H+ exchange activity in the proximal tubule luminal membrane would be increased in association with renal hypertrophy, altered glomerular hemodynamics, enhanced filtered load and tubular reabsorption of Na+, and stimulated Na+ pump activity in the basolateral membrane, previously reported characteristics of this experimental animal model. Amiloride-sensitive H+ gradient-dependent Na+ uptake and Na+ gradient-dependent H+ flux were increased in brush-border membrane vesicles from the streptozotocin-treated animals. Na+ gradient-dependent uptakes of phosphate, D-glucose, L-proline, and myoinositol were decreased in the drug-induced diabetic animals. These membrane transport alterations were not found when the streptozotocin-diabetic animals were treated with insulin.
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Human retroviruses have been causally associated with the development of the acquired immune deficiency syndrome (AIDS) in groups of individuals at high risk including intravenous drug users, hemophiliacs, and homosexual men. Aside from classic AIDS, homosexual men also develop persistent generalized lymphadenopathy (PGL) which is considered a part of the AIDS-related complex (ARC). We have isolated 70 strains of retroviruses related to human T-lymphotropic viruses type III (HTLV-III) from patients with PGL, AIDS, or ARC. analyses of sera from these patients indicated a high degree of serologic heterogeneity in the antibody titers and their reactivities toward various HTLV-III viral proteins. In addition, we have detected virus-neutralizing antibodies in approximately 50% of the serum samples tested from patients with PGL or AIDS. This is the first comprehensive virologic and serologic report on more than 100 patients studied at one institution in Los Angeles.
Fifteen neuroendocrine carcinomas of the skin (Merkel cell tumors) were stained within the constraints of tissue availability by the Grimelius method and immunohistochemically for keratin, neuron-specific enolase (NSE), carcinoembryonic antigen (CEA), S-100, common leukocyte antigen (CLA), met-enkephalin, bombesin, calcitonin, ACTH, gastrin, and somatostatin. Focal argyrophilia was present in 5 of 12 tumors. All tumors tested demonstrated immunoreactivity for NSE and 5 tumors were positive for keratin. One tumors appeared to demonstrate focal ACTH-like immunoreactivity, but otherwise no immunoreactivity for the above mentioned polypeptide hormones was noted in 11 completely studied tumors. One tumor contained histologically obvious areas of squamous differentiation in addition to areas of Merkel cell tumor. In various tumors, keratin immunoreactivity was present either in areas of histologically obvious squamous differentiation, in randomly scattered single cells not histologically identifiable as squamous, or in a paranuclear dot-like distribution. Immunoreactivity for CEA, S-100 and CLA was not present in any tumors. The lack of met-enkephalin and the presence of squamous differentiation in these tumors indicates multidirectional differentiation in a fashion not phenotypically typical of Merkel cells.
The initial rate (5 s) of Na+-dependent inorganic phosphate (Pi) uptake in brush-border membrane vesicles isolated from rat proximal tubule was decreased in metabolic acidosis, 0.42 +/- 0.02 vs. 0.59 +/- 0.05 nmol/mg protein, in vesicles from control animals. Phosphate, ammonium, and Ca2+ excretions were increased 100, 600, and 56%, respectively. These changes in brush-border Pi transport and urinary excretion of ions were largely dependent on intact adrenal glands. After adrenalectomy there were no significant changes in brush-border Pi transport, Pi, and Ca2+ excretion, whereas ammonium excretion increased only 300% compared with controls. When the glucocorticoid dexamethasone was administered to adrenalectomized animals, it mimicked the effects of metabolic acidosis both in the presence and the absence of metabolic acidosis. The initial rate of brush-border Pi transport was decreased by dexamethasone administration to 0.37 +/- 0.04 nmol/mg protein in adrenalectomized acidotic animals and 0.39 +/- 0.03 nmol/mg protein in adrenalectomized animals. Dexamethasone administered to adrenalectomized acidotic animals increased Pi, ammonium, and Ca2+ excretion 190, 690, and 23%, respectively. Dexamethasone administered to nonacidotic adrenalectomized animals increased Pi ammonium and Ca2+ excretion 165, 240, and 31%, respectively. We conclude that changes in Pi, ammonium, and Ca2+ excretion observed during metabolic acidosis were dependent on intact adrenal glands and that glucocorticoids administered to adrenalectomized acidotic or nonacidotic animals mimicked the changes observed in acidotic animals with intact adrenal glands.
Infusion of phosphate into thyroparathyroidectomized rats on a normal phosphorus diet caused a decrease in net phosphate reabsorption, even though the plasma concentration of phosphate continued to rise. This response was expressed at the level of the proximal tubule brush-border membrane and was coincident with a decrease in sodium-dependent phosphate uptake in membrane vesicles. Kinetic experiments indicated that the increased phosphate load caused a decrease in the Vmax of the membrane uptake system with no change in the apparent Km for phosphate. The infusion of phosphate resulted in a lowered plasma calcium concentration, and it was previously hypothesized that the inhibition of maximal phosphate reabsorption was mediated by the hypocalcemia. When the fall in plasma calcium was prevented by the simultaneous infusions of calcium and phosphate, the reduction in maximal phosphate reabsorption was blunted; however, the phosphate infusion-induced inhibition of brush-border membrane vesicle phosphate uptake was still evident. Thus a major discrepancy was found to the general concept that renal phosphate reabsorption in vivo correlated positively with sodium-dependent phosphate uptake activity in proximal tubule brush-border membrane vesicles. Several possible explanations to account for this anomaly were discussed. It was also found that calcium infusion into saline-infused thyroparathyroidectomized rats slightly increased maximal phosphate reabsorption but did not affect phosphate uptake in the membrane vesicles.
Serial histological sections of gingiva obtained from each of six advanced adult periodontitis, two localized juvenile periodontitis and two periodontally healthy patients were used for specific identification of bacteria within the oral epithelium and adjacent connective tissue. Healthy gingival biopsies served as controls. Sections from patients and control biopsies were Gram-stained and also screened with antibacterial sera associated with the peroxidase immunocytochemical technique for specific bacterial identification. The "Pop-off" electron microscopic technique was also used to further demonstrate the bacterial nature of peroxidase-stained material. In addition, the possible correlation between bacteria and areas of possible reduced keratinization was investigated. The results showed that sections of orthokeratinized healthy gingiva did not contain bacteria. Gram-stained sections from diseased sites contained large numbers of bacteria in the oral epithelium and adjacent connective tissue. Bacteroides gingivalis and to a lesser extent Capnocytophaga gingivalis were found in periodontitis, and Actinobacillus actinomycetemcomitans was found in juvenile periodontitis when the immunoperoxidase technique was used. The bacterial nature of peroxidase-stained material was confirmed by the "pop-off" technique. In the disease biopsies, bacterial presence was correlated with areas of reduced amounts of keratin suggesting that the oral epithelium may be a portal of entry for bacteria into gingival tissues.
Serum HSV-2 antibody in male from high and low incidence areas of cervical cancer was assayed by enzyme-immuno-slide method. The results show that the geometric mean titer of the serum HSV-2 antibody in the male from high incidence area (413.5) is significantly higher than that from the low incidence area (210.4) (P less than 0.01). It indicates that the high cancer incidence might be related to the high HSV-2 infection rate in the spouses of the cervical cancer patients.
Immunoreactivity for endocrine peptides (serotonin, gastrin, somatostatin, insulin, corticotropin, calcitonin, neurotensin, vasoactive intestinal peptide, and bombesin), cytoskeletal proteins (high and low molecular weight keratins), and tumor differentiation markers (chromogranin, neuron-specific enolase, carcinoembryonic antigen, S100 protein, and Grimelius stain) was sought on nine cervical and one vaginal poorly differentiated small-cell carcinoids. Dense-core secretory granules were ultrastructurally identified in all cases (seven of ten) in which tissue was available for electron microscopy. Immunoreactivity for endocrine secretory products was rarely noted, and only in a minority cell population (serotonin in two of ten). The majority of the tumors exhibited immunoreactivity for low molecular weight keratin (AE1/AE3 in eight of ten; CAM 5.2 in seven of nine), and three of ten tumors focally expressed high molecular weight keratin. Among the markers of neuroendocrine differentiation, neurospecific enolase was more frequently expressed (ten of ten) than chromogranin (five of ten) or argyrophilia (three of ten). Carcinoembryonic antigen was present in eight of ten tumors. S100 protein was absent in all cases. In summary, poorly differentiated small-cell carcinoids of the lower female genital tract, similarly to other small-cell endocrine tumors, occasionally exhibit focal glandular and squamoid differentiation, and only relatively infrequently or focally express immunohistochemically detectable endocrine secretory products, chromogranin, and argyrophilia.
Ninety-three cervical conization specimens with condyloma or intraepithelial neoplasia were stained by the peroxidase-antiperoxidase technique for involucrin. Diffuse, homogeneous suprabasal staining was observed in the ectocervical squamous mucosa and mature squamous metaplasia. In immature squamous metaplasia, staining was limited to cells with apparent squamous differentiation. Although diffusely reactive in the upper layers of condyloma and cervical intraepithelial neoplasia (CIN) grade I, the stain was uneven in the former and lacking in the parabasal layers of the latter. The staining intensity, distribution, and pattern were more variable in CIN grade II and grade III. With increasing severity, a patchy pattern with a mixture of reactive and nonreactive cells predominated. Although immunoreactivity with involucrin could not distinguish immature squamous metaplasia from neoplasia, the staining patterns in CIN correlated with extent of disease, degree of squamous differentiation, and cellular disorganization.
Fifty cases of non-Hodgkin's lymphoma (15 nodular and 35 diffuse) were studied to determine the sensitivity, specificity, and ease of several different immunoperoxidase methods. The methods included a rapid, simple one-step immunoperoxidase procedure on frozen sections compared with indirect immunoperoxidase technics on paraffin sections. The frozen-section immunoperoxidase technic stained 15 of 15 nodular lymphomas and 24 of 35 diffuse lymphomas for monoclonal light chain. The majority of the diffuse lymphomas that did not stain for light chains were morphologically and immunohistochemically consistent with T-cell lymphomas. The indirect method on B-5 and formalin-fixed tissues only rarely displayed monoclonal staining for nonplasmacytoid small cell lymphomas but did stain some large cell lymphomas and a majority of plasmacytoid lymphomas for monoclonal light chain. The frozen section technic presented in this report is sufficiently sensitive and reliable to detect immunoglobulins in any morphologic subtype of B-cell lymphoma, whereas paraffin-embedded tissues have only limited application.