Low-frequency stimulation reverses kindling-induced neocortical motor map expansion.

Repeated application of low-frequency stimulation can interrupt the development and progression of seizures. Low-frequency stimulation applied to the corpus callosum can also induce long-term depression in the neocortex of awake freely moving rats as well as reduce the size of neocortical movement representations (motor maps). We have previously shown that seizures induced through electrical stimulation of the corpus callosum, amygdala or hippocampus can expand the topographical expression of neocortical motor maps. The purpose of the present study was to determine if low-frequency stimulation administered to the corpus callosum could reverse the expansion of neocortical motor maps induced by seizures propagating from the hippocampus. Adult Long-Evans hooded rats were electrically stimulated in the right ventral hippocampus, twice daily until 30 neocortical seizures were recorded. Subsequently, low-frequency stimulation was administered to the corpus callosum once daily for 20 sessions. High-resolution intracortical microstimulation was then utilized to derive forelimb-movement representations in the left (un-implanted) sensorimotor neocortex. Our results show that hippocampal seizures result in expanded motor maps and that subsequent low-frequency application can reduce the size of the expanded motor maps. Low-frequency stimulation may be an effective treatment for reversing seizure-induced reorganization of brain function.

Diagnostic value of hepatocyte paraffin 1 antibody to discriminate hepatocellular carcinoma from metastatic carcinoma in fine-needle aspiration biopsies of the liver.

BACKGROUND: Diagnosing liver tumors by fine-needle aspiration biopsy is safe and accurate. However, there are cases that prove diagnostically difficult. Traditionally, immunostains for alpha-fetoprotein and polyclonal carcinoembryonic antigen have been used to distinguish adenocarcinomas from hepatocellular carcinomas (HCCs). In poorly differentiated tumors, these immunostains have limitations in both sensitivity and specificity. An hepatocyte-specific immunostain has been described in the surgical pathology literature. To the authors' knowledge, this hepatocyte antibody has not been studied in liver fine-needle aspiration biopsies. The authors examined the Hepatocyte Paraffin 1 (HP1) antibody for its diagnostic utility in this cytologic setting. METHODS: Cell-block material from 40 cases of HCC and 53 cases of metastatic adenocarcinoma were studied. Slides were stained for HP1 by the avidin-biotin complex method following antigen retrieval. The percentage of malignant cells that exhibited coarse granular staining in the cytoplasm was estimated for all cases of HCC, poorly differentiated HCC, and metastatic adenocarcinoma. RESULTS: HP1 was expressed in 83% of all HCCs but in only 56% of poorly differentiated HCCs. Only 2 of 53 (4%) of metastatic tumors expressed HP1. The overall sensitivity of HP1 was 79% and its specificity was 96%. CONCLUSION: HP1 was found to be a specific immunostain that may prove helpful in diagnosing all but the most undifferentiated liver tumors biopsied by fine-needle aspiration.

Differentiating large cell lymphoma from indolent small B-cell lymphoma in fine needle aspirates using p53, PCNA and transformed lymphocyte count.

OBJECTIVE: To determine the usefulness of proliferating cell nuclear antigen (PCNA), p53 protein expression and transformed lymphocyte count (TLC) as adjunctive tests to differentiate indolent small B-cell lymphoma from large cell lymphoma in fine needle aspiration biopsies. STUDY DESIGN: Aspirates of lymphoproliferative disorders from April 1993 to January 1997 were reviewed. The percentage of TLCs was determined on the Papanicolaou smear. The percentage and intensity of p53 and PCNA immunocytochemical staining was evaluated on cell block sections. These results were compared and correlated with the final diagnoses based on available morphology, flow cytometry and clinical history. RESULTS: There were 40 cases of non-Hodgkin's lymphoma and 12 reactive lymph nodes. Adequate cell blocks were available on 16 large cell lymphomas, 7 grade 1-2 follicular center cell lymphomas, 6 mucosal associated lymphoid tissue lymphomas, 2 small lymphocytic lymphomas and 2 mantle cell lymphomas. Average TLC and p53 nuclear staining was highest in large cell lymphomas (57% TLC and 24% p53), followed by grades 1 and 2 follicular lymphomas (14% TLC and 15% p53) and lowest in other indolent lymphomas (< 10% TLC and < 1% p53). Average PCNA staining was highest in large cell lymphomas (46%) and lowest in small lymphocytic lymphomas (7%); however, TLC was the best parameter for differentiating large cell lymphoma from indolent small B-cell lymphoma. CONCLUSION: TLC differentiated large cell lymphoma from indolent small B-cell lymphoma better than either p53 or PCNA alone or in combination. Significant overlap between categories limits usefulness of these immunocytochemical stains for differentiating these entities.

Diagnosis of lymphoma by fine-needle aspiration cytology using the revised European-American classification of lymphoid neoplasms.

BACKGROUND: Recent changes in the classification of non-Hodgkin lymphoma (NHL) emphasize the diagnostic importance of cytomorphology, immunophenotyping, and molecular findings in addition to histology. These changes have allowed for a greater role of fine-needle aspiration cytology (FNA) in the diagnosis of NHL. METHODS: A review of the English language literature regarding the use of FNA in the cytodiagnosis of lymphoma was performed. The revised European-American classification of lymphoid neoplasms (REAL) was reviewed in the context of its adaptability to the cytologic diagnosis of lymphoid neoplasms. RESULTS: FNA is being used more frequently in the diagnosis, staging, and follow-up of lymphoma whenever supportive studies are readily available. Cytomorphologic, immunophenotypic, and molecular criteria as well as pitfalls in the diagnosis of lymphoma by FNA have been delineated. Information was compiled into tables to facilitate correlation of criteria with the proposed REAL system. CONCLUSIONS: Many cases of NHL can be diagnosed and subclassified by FNA when there is adequate immunophenotypic information. Cancer (Cancer Cytopathol)