Ultrasonic backscatter coefficient quantitative estimates from Chinese hamster ovary cell pellet biophantoms

A cell pellet biophantom technique is introduced, and applied to the ultrasonic backscatter coefficient (BSC) estimate using Chinese hamster ovary (CHO) cells. Also introduced is a concentric sphere scattering model because of its geometrical similarities to cells with a nucleus. BSC comparisons were made between the concentric sphere model and other well-understood models for mathematical verification purposes. BSC estimates from CHO cell pellet biophantoms of known number density were performed with 40 and 80 MHz focused transducers (overall bandwidth: 26-105 MHz). These biophantoms were histologically processed and then evaluated for cell viability. Cell pellet BSC estimates were in agreement with the concentric sphere model. Fitting the model to the BSC data yielded quantitative values for the outer sphere and inner sphere. The radius of the cell model was 6.8 ± 0.7 μm; the impedance of the cytoplasm model was 1.63 ± 0.03 Mrayl and the impedance of the nuclear model was 1.55 ± 0.09 Mrayl. The concentric sphere model appears as a new tool for providing quantitative information on cell structures and will tend to have a fundamental role in the classification of biological tissues.

Three-dimensional reconstructive analysis of intracytoplasmic lumina found in ependymomas

Three-dimensional reconstructive analyses revealed that the intracytoplasmic lumina found in ependymomas were actually formed by subsidence of an extracellular membrane, resembling a volcano. This finding was compatible with cytologic and electron microscopic findings. In addition, there were many tiny thorns resembling a holly leaf on the extracellular membrane, such that cilia and microvilli on the cellular membrane discontinued cell-to-cell tight junctions.

Ultrastructural localization of intraneuronal Abeta-peptide in Alzheimer disease brains

Autopsied brain tissue from Alzheimer's disease patients and old non-demented controls was studied after immunocytochemistry with the 4G8 monoclonal antibody that recognizes amyloid-beta peptides. Intraneuronal 4G8-positive reaction product was detected in all of the studied brains. The same brain regions in the Alzheimer's disease samples consistently showed both more immunopositive neurons and more stained reaction product per neuron than those from the non-demented brains. Ultrastructurally, the immunopositive reaction product accumulated in clusters of cytoplasmic elements that had a lipofuscin-like appearance, showed a fibrogranular content and were also closely apposed to lipid droplets located either on their periphery or within them. The most strongly 4G8-immunopositive elements had diffuse limits with their fibrogranular content free in the cytoplasm, whereas elements either without or showing only light immunoreaction had a limiting membrane. All immunopositive neurons displayed a similar pattern of clumping heterochromatin. The hypothetical neurotoxic role of intraneuronal amyloid-beta peptides free in the cytoplasm is discussed as is the possible relationship between the amyloid-beta peptides recognized by the 4G8 antibody and the lipid droplets which would presumably contain esterified cholesterol.

"Indeterminate" cystic lesion of the kidney partially lined by small cells with clear cytoplasm--malignant or benign?

Complex renal cysts, which present radiographically as "indeterminate for malignancy" (Bosniak category III), can prove challenging both pathologically and clinically. We report a case of a renal cyst that, by standard radiographic and histologic criteria, should have been diagnosed as a malignant cystic renal cell carcinoma. However, the cytogenetic profile appeared more closely consistent with cystic renal adenoma or low-grade papillary renal cell carcinoma--tumors with limited metastatic potential. We postulate that other, similarly complex, renal cysts might also be more precisely defined by meticulous histopathologic examination, supported by cytogenetic study.

99mTc annexin V imaging of neonatal hypoxic brain injury

BACKGROUND AND PURPOSE

Delayed cell loss in neonates after cerebral hypoxic-ischemic injury (HII) is believed to be a major cause of cerebral palsy. In this study, we used radiolabeled annexin V, a marker of delayed cell loss (apoptosis), to image neonatal rabbits suffering from HII.

METHODS

Twenty-two neonatal New Zealand White rabbits had ligation of the right common carotid artery with reduction of inspired oxygen concentration to induce HII. Experimental animals (n=17) were exposed to hypoxia until an ipsilateral hemispheric decrease in the average diffusion coefficient occurred. After reversal of hypoxia and normalization of average diffusion coefficient values, experimental animals were injected with (99m)Tc annexin V. Radionuclide images were recorded 2 hours later.

RESULTS

Experimental animals showed no MR evidence of blood-brain barrier breakdown or perfusion abnormalities after hypoxia. Annexin images demonstrated multifocal brain uptake in both hemispheres of experimental but not control animals. Histology of the brains from experimental animals demonstrated scattered pyknotic cortical and hippocampal neurons with cytoplasmic vacuolization of glial cells without evidence of apoptotic nuclei by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. Double staining with markers of cell type and exogenous annexin V revealed that annexin V was localized in the cytoplasm of scattered neurons and astrocytes in experimental and, less commonly, control brains in the presence of an intact blood-brain barrier.

CONCLUSIONS

Apoptosis may develop after HII even in brains that appear normal on diffusion-weighted and perfusion MR. These data suggest a role of radiolabeled annexin V screening of neonates at risk for the development of cerebral palsy.

Nuclear localization of 111In after intravenous injection of [111In-DTPA-D-Phe1]-octreotide in patients with neuroendocrine tumors

Treatment with tumor-targeting substances is currently being evaluated in clinical trials. For patients with neuroendocrine tumors expressing somatostatin receptors, the 111In-labeled somatostatin analog [diethylenetriaminepentaacetic acid (DTPA)-DPhe1]-octreotide has been used with promising results. To further investigate the clinical effect of the injected conjugate, we analyzed the cellular distribution of 111In by ultrastructural autoradiography.

METHODS

Seven patients with somatostatin receptor-expressing midgut carcinoid tumors scheduled for abdominal surgery were investigated by somatostatin receptor scintigraphy. During operation, tumor tissue samples and samples of normal intestine were collected, fixed, and processed for electron microscopy. A thin layer of film emulsion was applied on sections and after the exposure film was developed. The cellular distribution of silver precipitations indicating the presence of isotope was evaluated.

RESULTS

Cell surface receptor binding and internalization of [111In-DTPA-D-Phe1]-octreotide in the tumor cells was easily revealed by silver precipitations in the film. Multiple silver grains were seen at the plasma membrane, in the cytoplasmic area among secretory granules and vesicular compartments, and in the perinuclear area. Silver grains were also regularly located in the nucleus. For all patients, the silver precipitation patterns from 111In decay were identical in all examined cells from removed tumors, and in most cells 111In could be seen in the nucleus. The specificity of the silver reaction products is supported by the observation that enterocytes in intestinal tissue specimens from near the tumor did not show any silver grains and no background labeling was seen in the plastic.

CONCLUSION

After internalization through the somatostatin receptor system, 111In is translocated to the perinuclear area and into the nucleus. Whether the nuclide is still conjugated to the intact somatostatin analog or to part of it cannot be evaluated in this study. Despite the short irradiation range of 111In, the nuclear localization can explain its clinical effectiveness. The results from this study suggest that [111In-DTPA-D-Phe1]-octreotide may act as a powerful tumor cell-targeting substance.

Structural peculiarities of the tissue formed in modelling of the articular surface

A model of articular cavity with smooth cover was produced by influence of shape-forming element on regenerating bone tissue. Morphological, ultrastructural, histochemical, and biochemical peculiarities of the tissue of the formed articular surface are described.

Nickel binding and uptake in thymocytes and peripheral blood lymphocytes of nickel-allergic and control subjects

In the present investigation, the binding and uptake of 63NiCl2 was studied in human thymocytes and in peripheral blood lymphocytes from nickel-allergic and control subjects. A direct binding of the isotope to the lymphocyte membranes was shown by autoradiography. This binding was not more marked in peripheral blood lymphocytes of nickel-allergic subjects than in those of control subjects or in thymocytes. As judged by liquid scintillation, there was an uptake of isotope both into the nucleus and cytoplasm of the cells, being low compared to the medium activity. The uptake into blood lymphocyte nuclei of nickel-allergic subjects was significantly (p less than 0.05) higher than into those of the control group. The present findings indicate a direct action of nickel on lymphocytes, which might be of importance for DNA synthesis stimulation.

[Radioactive labeling of cytoplasmic hormone receptors. Determination and clinical significance of estrogen and progesterone receptors]

Neither autoradiography nor in vitro labeling of thin sections of tumor tissue can be used for the quantitative determination of radioactive labeled cytoplasmic hormone receptor. The acknowledged method for his purpose is the DCC (Dextran Coated Charcoal) method. Hormone receptor estimations are routinely used to predict those patients with hormone-dependent tumors who will respond to endocrine therapy. Some 80% of patients with positive estrogen and progesterone receptor show objective remissions after endocrine therapy. Receptor determinations are carried out routinely in patients with mammary, uterine or ovarian carcinoma to identify those subjects who would benefit most from endocrine therapy.