Automated iterative three-dimensional registration of positron emission tomography images

Two types of image similarity measures, the sum of absolute differences (SAD) and the stochastic sign change (SSC), were compared for three-dimensional registration of images from PET. To test the accuracy of both registration methods, 30 FDG brain studies, 40 13N-ammonia cardiac studies and 20 FDG liver tumor studies (where each image set contained 15 image planes, 128 x 128 pixels per plane) were made into worse case conditions by creating image sets of low counts and extreme defects. These images were then registered to the reference images that had been moved in three dimensions into a random set of known translations, rotations and normalization factors (x, y, z, theta, rho, sigma, nf). Neither method required any external fiduciary markers or operator interventions to register a set of images. The optimization of the image similarity (using the SAD or SSC) was performed with the simplex method and registration was completed within 10 min of computation time on a low-end workstation. Overall, the SAD method had an average inplane (x, y) registration error of 0.5 +/- 0.5 mm, a z-axis registration error of 1.1 +/- 1.1 mm, an inplane rotational error of 0.5 +/- 0.4 degrees, an out-of-plane rotational error of 1.1 +/- 1.2 degrees and a normalization factor error of 0.015 +/- 0.016. The SSC method had an average inplane (x, y) registration error of 0.6 +/- 0.5 mm, a z-axis registration error of 1.1 +/- 1.1 mm, an inplane rotational error of 0.7 +/- 0.5 degrees, an out-of-plane rotational error of 1.0 +/- 1.2 degrees and a normalization factor error of 0.014 +/- 0.014. This study demonstrates that either the SAD or SSC method for measuring image similarity, combined with the simplex method for function optimization, are accurate methods for registration of a wide variety of PET images including low count studies and those with marked interval changes in the pattern of count distribution.

Quantification and parametric imaging of renal cortical blood flow in vivo based on Patlak graphical analysis

Patlak graphical analysis was applied to quantify renal cortical blood flow with N-13 ammonia and dynamic positron emission tomography. Measurements were made in a swine model of kidney transplantation with a wide range of normal and abnormal renal blood flows (N = 57 studies) and in 20 healthy human volunteers (N = 45 studies). Estimates of renal cortical blood flow by the Patlak method were compared to those from a two-compartment model for N-13 ammonia. In addition, estimates of renal cortical blood flow by the N-13 ammonia PET approach were compared in 10 normal human volunteers to estimates by the metabolically inert, freely diffusible O-15 water and a one-compartment model. Patlak graphical analysis estimates of renal cortical blood flow correlated linearly with the standard two-compartment model in pigs (y = -0.05 + 1.01x, r = 0.99) and in humans (y = 0.57 + 0.88x, r = 0.93). Estimates of renal cortical blood flow by O-15 water in human volunteers were also linearly correlated with those by N-13 ammonia and the Patlak graphical analysis (y = 0.71 + 0.84x, r = 0.86). Renal cortical blood flow estimates were highly reproducible both with N-13 ammonia and O-15 water measurements in humans. It is concluded that the Patlak graphical analysis with N-13 ammonia dynamic positron emission tomograpic imaging renders accurate and reproducible estimates of renal cortical blood flow. Moreover, the graphical analysis approach is 1,000 times faster than the standard model fitting approach and suitable for generating parametric images of renal blood flow in the clinical setting.

Ex vivo clonotype primer-directed gene amplification to identify malignant T cell repertoires

A novel strategy that utilizes input genomic DNA and overcomes limitations encountered with traditional RNA reverse transcription-polymerase chain reaction (PCR) amplification methodology is described to screen for T cell receptor (TCR) repertoires. The methodology has been developed to identify individual T cell clonotypes with regard to their unique receptor beta chain variable/diversity/joining (VDJ) region gene rearrangement. The technique avoids preselection for a given antigen specificity and is therefore independent of artificial bias introduced by in vitro cell population expansion. This technique was used to detect and identify genetically of malignant clones from heterogeneous mononuclear cell populations from an array of hemato-oncological disorders, including mycosis fungoides/Sézary Syndrome, adult T cell leukemia, and large granular lymphoproliferative disease. An initial primary PCR, directed by a TCR-J beta generic primer and a complement of family-specific TCR-V beta primers, defines predominant T cell receptor variable gene usage. Use of a TCR-J beta generic primer supplants the use of a constant region primer anchor and thus eliminates the need to target mRNA. The process of variable gene screening also expedites gene sequencing. By sequencing through the VDJ juxtaposed region, i.e., the third complementarity determinant region, clonotype-specific primers are developed and used in a secondary clonotype primer-directed PCR (CPD-PCR) to detect, with extreme sensitivity and specificity, unique T cell clonal repertoires. Analysis of the products of the CPD-PCR permits the detection of a single malignant cell among one million polyclonal cells and supercedes the constraints of prior studies that provide a limited evaluation of family variable gene repertoire usage. This strategy may be applied in the detection of minimal residual disease, in surveillance after induction of disease-free states, and in analyzing the effectiveness of purging autologous bone marrow of malignant clones.

Bone metabolic activity measured with positron emission tomography and [18F]fluoride ion in renal osteodystrophy: correlation with bone histomorphometry

We evaluated the bone metabolic activity in patients with renal osteodystrophy using positron emission tomography and [18F]fluoride ion. Eight patients had secondary hyperparathyroidism (HPT), and three had low-turnover bone disease. Eleven normal subjects were also studied, and three of the eight HPT patients were reevaluated after therapy. A rate constant (K) describing the net transport of [18F] fluoride ion into a bound compartment in bone was calculated using both a three-compartment model and Patlak graphical analysis. Values of K were compared with biochemical data and with histomorphometric indices. The results indicate that K is significantly higher (P < 0.01) in HPT patients than in normal subjects and patients with low-turnover bone disease. Values of K correlated with serum alkaline phosphatase (r = 0.81) and PTH (r = 0.93) levels and with histomorphometric indices of bone formation rate (r = 0.84, P < 0.01) and eroded perimeter (r = 0.77, P < 0.05). Values of K decreased by 40 and 30%, respectively, in two patients who underwent parathyroidectomy and medical therapy. Positron emission tomography studies of bone using [18F]fluoride ion can differentiate low turnover from high turnover lesions of renal osteodystrophy and provide quantitative estimates of bone cell activity that correlate with histomorphometric data.

Hallervorden-Spatz syndrome in two siblings diagnosed by the clinical features and magnetic resonance imaging (MRI)

Hallervorden-Spatz syndrome (HSS) is a heredodegenerative disorder characterized by both progressive pyramidal and extrapyramidal signs, dysarthric speech, and mental deterioration. No diagnostic biochemical test is yet available, and diagnosis of HSS can be confirmed only at autopsy by the characteristic neuropathology including abnormal iron storage, disordered myelination, and loss of brain substance. We present two siblings with clinical features consistent with HSS, in whom magnetic resonance imaging (MRI) demonstrated the deposition of iron in the globus pallidus and the substantia nigra thus allowing an antemortem diagnosis of HSS.

Positron emission tomography with fluorodeoxyglucose to evaluate tumor response and control after radiation therapy

PURPOSE

Following radiation therapy, evaluation of viable tumor can often be difficult with anatomic imaging criteria (tumor size alone). In this study, the utility of biochemical imaging with the glucose analog 2-[F-18]fluoro-2-deoxy-D-glucose and positron emission tomography was investigated in patients treated with radiation therapy.

METHODS AND MATERIALS

Between 1990 and 1992, 19 patients were studied, including 15 patients with head and neck cancer, (4 oropharynx, 4 sinus, 3 larynx, 2 hypopharynx, 2 oral cavity [one patient], 1 nasopharynx), and 4 patients with breast cancer. Post-radiation positron emission tomography with 2-[F-18]fluoro-2-deoxy-D-glucose studies were done in all patients, with 9 head and neck patients receiving pre-radiation positron emission tomography with 2-[F-18]fluoro-2-deoxy-D-glucose scans as well. Results were correlated with other imaging techniques and pathology.

RESULTS

Positron emission tomography with 2-[F-18]fluoro-2-deoxy-D-glucose detected head and neck primary tumors and lymph node metastases in all nine pre-radiation scans, while magnetic resonance imaging failed to detect two primary tumors. Serial positron emission tomography with 2-[F-18]fluoro-2-deoxy-D-glucose showed a significant decrease in tumor activity after radiation therapy, compared to pre-radiation levels, (p < 0.05), except for two patients with increased uptake at the primary site. Biopsies of these two patients showed persistent/recurrent disease after radiation therapy, which was not detected by magnetic resonance imaging. Six additional head and neck patients, with suspicious examination and inconclusive magnetic resonance imaging, were imaged with positron emission tomography after radiation therapy only. Five patients had increased positron emission tomography activity, with corresponding biopsies positive in four patients, and negative in one patient with clinically worsening symptoms. The remaining sixth patient had minimal and stable positron emission tomography uptake, and is improving clinically. Four patients had mammogram findings suspicious for recurrence after conservation treatment for breast cancer. Positron emission tomography with 2-[F-18]fluoro-2-deoxy-D-glucose showed no focal activity in the breast in two patients, and increased activity in the area suspicious for recurrence in the other two patients. Biopsies correlated with positron emission tomography results.

CONCLUSION

Changes and presence of positron emission tomography with 2-[F-18]fluoro-2-deoxy-D-glucose activity correlated with pathologic findings in head and neck and breast cancer patients in this series. In patients with elevated or rising positron emission tomography activity after radiation therapy, persistent or recurrent disease was found in 89% of patients, (8/9). Magnetic resonance imaging did not detect the head and neck recurrences, and mammography was suspicious in patients with both benign and malignant breast changes after radiation therapy. In addition, our data indicate that in head and neck patients with pre-radiation positron emission tomography scans, a significant decrease in activity should occur after radiation therapy, if local control is to be expected.

Positron emission tomography: a new method for determination of renal function

Positron emission tomography (PET) is a newly evolving diagnostic modality that has been widely used in many facets of clinical medicine, but whose use in the diagnosis and management of disorders of the kidney has not been previously described. Employing the radiotracer N-13 ammonia, flow-dependent extraction of this compound after intravenous injection was used to measure renal blood flow (RBF) in a swine model (N = 10). A mean baseline value of 3.16 ml./min./gm. kidney was obtained with this method, in close agreement with values previously reported using established invasive techniques. Four conditions known to affect RBF were also studied to determine the ability of PET to detect changes in RBF. Kidneys were subjected to varying durations of warm ischemia, demonstrating a progressive decrease in RBF with increasing ischemic insult, with return to normal significantly impaired in animals exposed to the greatest degree of ischemia (180 minutes versus 150 or 120 minutes ischemia). Cross-transplant between animals produced acute allograft rejection and a corresponding marked decrease in RBF that failed to normalize. After unilateral nephrectomy, RBF increased two-fold in the remaining kidney by 7 days (R = 0.79), as predicted for compensatory renal hypertrophy. Lastly, there was an inverse, linear relationship between toxic cyclosporine level and RBF (R = 0.68), indicative of vascular-mediated cyclosporine nephrotoxicity. Positron emission tomography is safe and efficient, and yields an accurate measurement of RBF in several important physiologic states. The development of PET as a quantitative measure of renal function is promising.

Direct evidence for the role of COOH terminus of mouse mammary tumor virus superantigen in determining T cell receptor V beta specificity

It has recently been shown that open reading frames in the 3' long terminal repeats of mouse mammary tumor viruses encode superantigens. These viral superantigens (vSAGs) stimulate most T cells expressing appropriate V beta s almost regardless of the rest of the variable components of the T cell receptors (TCR) expressed by those cells. vSAGs produce a type II integral membrane protein with a nonessential short cytoplasmic domain and a large glycosylated extracellular COOH-terminal domain, which is predicted to interact with major histocompatibility complex class II molecules and the TCR. The transmembrane region of vSAG also has an internal positively charged lysine residue of unknown significance. A set of chimeric and mutant vSAG genes has been used in transfection experiments to show that only the extreme COOH-terminal portion of vSAGs determine their TCR V beta specificities, and to show that the lysine residue in the transmembrane domain is not essential for the function of vSAG.

Cancer detection with whole-body PET using 2-[18F]fluoro-2-deoxy-D-glucose

OBJECTIVE

This study was done to determine the feasibility and potential utility of whole-body PET using the glucose analogue 2-[18F]fluoro-2-deoxy-D-glucose (FDG) for the detection of primary malignancies and metastatic lesions.

MATERIALS AND METHODS

This was a prospective, nonrandomized study of whole-body FDG-PET imaging carried out at a large university teaching hospital in Los Angeles, CA, U.S.A. The study group consisted of all patients referred for PET imaging (87) with a suspected diagnosis of primary or recurrent malignancy and who had eventual histological confirmation of their lesions.

RESULTS

In the 87 patients, whole-body PET studies were positive (presence of focal FDG uptake relative to surrounding tissues uptake) in 61 of 70 patients (87%) with subsequent biopsy-confirmed primary or recurrent malignant lesions, including carcinomas of breast, lung, ovary, prostate, colon, urinary bladder, and gallbladder origin, as well as malignant melanoma, carcinoid, osteosarcoma, lymphoma, and spinal cord astrocytoma. The PET images revealed no focal hypermetabolism at the known site of tumor in patients with primary prostate carcinoma (two), microscopic ovarian carcinoma (two), breast carcinoma (one), low-grade carcinoid tumors (two), and one patient with recurrent microscopic osteogenic sarcoma. The PET studies detected the primary lesion in 15 of 17 patients with breast carcinoma and in 6 of 6 patients with primary lung carcinoma. Of the 17 patients with benign biopsies, 13 patients had FDG-PET studies without focal areas of uptake.

CONCLUSION

Because of the high glycolytic rate of malignant tissue, the whole-body FDG-PET technique has promise in the detection of a wide variety of both primary and metastatic malignancies. The presence of FDG uptake in benign inflammatory conditions may limit the specificity of the technique. The sensitivity for the detection of malignant lesions was 87% and the positive predictive value was 94%. The whole-body FDG-PET method is promising both in determining the nature of a localized lesion and in defining the systemic extent of malignant disease.

An animal model for in vivo evaluation of tumor glycolytic rates with positron emission tomography

We developed a method for evaluating tumor glycolytic rates in vivo with nude mice injected with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) and a dedicated animal positron emission tomography (PET) scanner. Animals were injected with NR-6 mouse fibroblast tumor cell lines. When tumors achieved a large enough size to be macroscopically visible, quantitative measurements of FDG uptake in vivo were obtained, using both standard nonlinear regression with the FDG tracer kinetic model to generate estimates of model parameters, including KNLR, the rate constant for net phosphorylation of FDG. Additionally, we determined the values of KPAT, the rate constant for net phosphorylation of FDG measured with a non-iterative graphical method. Estimates of K were highly correlated (r = 0.95) with both methods, and parametric images of KPAT demonstrate both the tumor location and size, but are also scaled in units of phosphorylation of FDG. The method is suitable for serial studies of tumor glucose metabolism during and after therapeutic interventions, such as chemotherapeutic trials.

Identification of surface-exposed B-cell epitopes recognized by Haemophilus influenzae type b P1-specific monoclonal antibodies

A panel of P1 synthetic peptides was synthesized to map the surface-exposed epitopes of Haemophilus influenzae type b outer membrane protein P1 recognized by three murine monoclonal antibodies (MAbs 7C8, 3E12, and 6B1). By using peptide-specific enzyme-linked immunosorbent assays, MAbs 6B1, 7C8, and 3E12 were shown to recognize distinct epitopes localized within residues 60 to 88, 165 to 193, and 400 to 437 of mature P1, respectively. Since MAb 7C8 was shown previously to be protective against certain H. influenzae type b subtypes in the infant rat model of bacteremia, its cognate epitope was further characterized by using truncated peptide analogs. Fine mapping of the 7C8 epitope by competitive inhibition studies revealed that it was localized within residues 184 and 193.

Correlation of ultrasound and renal scintigraphy in children with unilateral hydronephrosis in primary workup

Ultrasound accurately detects hydronephrosis in infants and children, while nuclear medicine techniques quantify relative renal function in addition to characterizing the urodynamic relevance of hydronephrosis. This prospective study was undertaken to examine the relationship between ultrasound morphological findings and relative renal function, quantified with dynamic 99mtechnetium mercaptotriacetylglycine imaging, in the initial diagnostic workup of children with unilateral hydronephrosis. The ultrasound grade of hydronephrosis and relative renal function ipsilateral to the hydronephrosis were inversely related, indicating that with more severe hydronephrosis ultrasound fails to estimate the potential reduction of relative kidney function. Because renal function is not necessarily affected by hydronephrosis, renal scintigraphy is indicated to assess the functional status of hydronephrotic kidneys.

Factors affecting myocardial 2-[F-18]fluoro-2-deoxy-D-glucose uptake in positron emission tomography studies of normal humans

The goal of this study was to identify the anatomic and physiologic factors affecting left ventricular myocardial 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) uptake and myocardial glucose utilization rates (MRGlc) in normal humans. Eighteen healthy male volunteers were studied in the fasting state (4-19 h) and 16 after oral glucose loading (100 g dextrose) with positron emission tomography (PET) and FDG. Substrate and hormone concentrations were measured in each study. The kinetics of myocardial FDG uptake were evaluated using both a three-compartment model and Patlak graphical analysis. Systolic blood pressures and rate pressure products were similar in the fasting and postglucose states. MRGlc averaged 0.24 +/- 0.17 mumol/min/g in fasting subjects and rose to 0.69 +/- 0.11 mumol/min/g after glucose loading. Phosphorylation rate constant, k3, and MRGlc were linearly related (P < 0.001). Increases in MRGlc following glucose loading were correlated with plasma glucose, insulin and free fatty acid concentrations, ratios of insulin to glucagon levels, and influx rate constants of FDG. Glucose loading improved the diagnostic image quality due to more rapid clearance of tracer from blood and higher myocardial FDG uptake. When MRGlc, glucose and insulin concentrations, and insulin to glucagon ratios exceeded 0.2 mumol/min/g, 100 mg/dl, 19 microU/ml, and 0.2 microU/pg, respectively, myocardial uptake of FDG was always adequate for diagnostic use. FDG image quality and MRGlc were similar after relatively short (6 +/- 2 h) and overnight (16 +/- 2 h) fasting. Significant (P < 0.05) regional heterogeneity of myocardial FDG uptake and MRGlc was observed in both the fasting and the postglucose studies. MRGlc and FDG uptake values in the posterolateral wall were higher than those in the anterior wall and septum. Thus, both 6-h and overnight fasts resulted in similarly low myocardial glucose utilization rates. While MRGlc and myocardial FDG uptake depended on plasma glucose, free fatty acid, and insulin concentrations, the results also suggest an additional dependency on plasma glucagon levels. Regional heterogeneities in myocardial FDG uptake and MRGlc are evident and independent of the subjects' dietary state. These regional heterogeneities need to be considered in studies of patients with cardiac disease.

A simplified method for quantification of myocardial blood flow using nitrogen-13-ammonia and dynamic PET

The utility of Patlak graphical analysis was investigated for quantification of regional myocardial blood flow (MBF) and for generating parametric images of MBF with 13N-ammonia and dynamic PET imaging in dogs and humans. MBF was estimated by a two-compartment model fit of the initial 2 min of the kinetic data and by Patlak graphical analysis of the initial 2, 3, or 4 min of data. In 11 dog studies, MBF by compartmental model fitting linearly correlated with MBF by microspheres (correlation coefficient (r) = 0.99, slope = 0.92) and by Patlak graphical analysis (r = 0.99, slope = 0.90). In 10 normal human studies, MBF obtained by the Patlak graphical analysis agreed well with MBF obtained by the compartmental model fitting (r = 0.96, slope = 1.04). Good agreement of the MBF estimates was also observed in 10 coronary artery disease patient studies (r = 0.96). Patlak graphical analysis permitted generation of parametric images of MBF. The parametric images of MBF, in units of ml/min/g, are of good image quality and have relatively low noise levels. We conclude that regional MBF can be noninvasively and conveniently measured with dynamic 13N-ammonia PET using either a two-compartment model or Patlak graphical analysis. MBF parametric images generated with the Patlak graphical analysis both map the distribution and quantitate the magnitude of myocardial perfusion abnormalities.

The bacterial and mouse mammary tumor virus superantigens; two different families of proteins with the same functions

In conclusion, the bacterial toxins are completely unlike the MTV superantigens in primary sequence and structure. The former are soluble globular proteins which do not have to be proteolytically cleaved before they act. The latter are synthesized as type II membrane proteins and may be clipped before they reach the cell surface and act to stimulate T cells. Table III summarizes the similarities and differences between the two sets of superantigens. The most notable quality of these molecules is that both sets of families have developed strategies whereby they bind to Class II and engage V beta. As far as the microorganisms which produce them are concerned, these two properties appear to be essential since they are absolutely conserved over proteins of a number of different structures. Several questions can now be addressed as follows. a. Why do all known superantigens bind to Class II? For the microorganism which produces them, the function of superantigens appears to be T-cell and perhaps directly or indirectly B-cell and macrophage stimulation. Activation of virgin T cells requires engagement with antigen plus MHC on professional antigen-presenting cells. Unlike other cell surface proteins, for example Class I, most Class II in animals is expressed on such cells. Therefore it is likely that superantigens have evolved to engage Class II because presentation to T cells by Class II-bearing cells offers the superantigen the best chance of activating its target T cells. b. Why do superantigens engage TCR V beta and not V alpha or CD3? It is possible that superantigens bind to the V beta portion of the TCR rather than V alpha because the latter does not have a consistently well exposed face for engagement. The fact that it is perhaps relatively easier to produce anti-V beta rather than anti-V alpha antibodies supports this idea. We have shown that N-glycosylation of V beta can interfere with recognition by vSAGs (Pullen et al. 1991), perhaps glycosylation of V alpha tends to conceal otherwise available sites. As far as C beta, C alpha or CD3 engagement is concerned, this may be just too dangerous for MTVs. The role of MTVs SAgs in the life history of the virus seems to be to stimulate T cells in the suckling recipient and thereby create a pool of activated lymphocytes in which the virus may survive until the mouse gives birth and transmits the virus to her own progeny (Hainaut et al. 1990, Golovkina et al. 1992).(ABSTRACT TRUNCATED AT 400 WORDS)

Whole body skeletal imaging with [18F]fluoride ion and PET

Using our recently reported whole body PET imaging technique, we performed whole body PET studies of the skeletal system with [18F]fluoride ion in 19 patients with a range of malignant and benign skeletal conditions and in 19 normal male volunteers. The technique produces two-dimensional projection images of the entire skeletal system ("a PET bone scan"), in addition to coronal, sagittal, and axial tomographic images of the skeletal system. The tomographic images had a 13% higher lesion detection sensitivity than the projection images. Whole body PET skeletal imaging with [18F]fluoride ion is technically feasible, provides images of excellent quality, and may be coupled with more quantitatively precise kinetic PET [18F]fluoride ion studies (over limited regions of the body) when numerical estimates of skeletal [18F]fluoride ion uptake are desired. The method is potentially useful in clinical applications where the high resolution and numerical precision of PET are of particular value (e.g., in accurately defining the anatomic location and extent of lesions and in assessing changes in bone metabolism on serial studies).

Extracranial head and neck: PET imaging with 2-[F-18]fluoro-2-deoxy-D-glucose and MR imaging correlation

The aim of this study was to define and quantitate the normal anatomy of the extracranial head and neck with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET). This information was used to study 12 patients with primary squamous cell carcinomas. In all cases, the lymphoid tissue of the Waldeyer ring and the palatine and lingual tonsils could be differentiated from the airway, striated muscle, osseous structures, and salivary glands. Striated muscle had markedly less activity than lymphoid or salivary gland tissue. In the 12 patients with primary tumors, FDG PET depicted the tumor as an area of increased activity significantly higher than that of normal tissue. In one instance, FDG PET allowed detection of a tumor not seen at magnetic resonance (MR) imaging or computed tomography. Of the 34 lymph nodes positive for carcinoma, 24 were positive according to MR size criteria and 25 were detected with FDG PET. FDG PET allowed detection of three nonenlarged metastatic nodes that were negative at MR imaging.

Identification of T-cell epitopes on E2 protein of rubella virus, as recognized by human T-cell lines and clones

T-cell epitopes on the E2 protein of rubella virus were studied by using 15 overlapping synthetic peptides covering the E2 protein sequence. The most frequently recognized epitopes on E2 were E2-4 (residues 54 to 74), with 5 of 10 tested T-cell lines responding to it. Two CD4+ cytotoxic T-cell cloned isolated from one T-cell line responded strongly in proliferation assays with peptide E2-4 and were cytotoxic to target cells presenting the E2-4 determinant. Truncated peptides contained within the E2-4 peptide sequence were used to define the T-cell determinants. Results indicated that amino acid residues 54 to 65 were directly involved. Human cell lines with different HLA phenotypes were tested for the capacity to present the antigenic determinants. The results suggested that recognition of peptide E2-4 by T-cell clones was associated with HLA DR7.

The role of positron emission tomography in oncology and other whole-body applications

Imaging and quantifying biochemical and physiological processes with PET clearly has major potential significance for all organ systems and many disease states. Although the full utility and potential of emerging new applications of PET in organs other than the heart and brain must be demonstrated in basic and clinical research studies, the rapidly accumulating aggregate experience in oncology in particular, and in other organ systems and disease states as well, indicates that PET is now truly becoming a modality of both clinical and investigative use for the body as a whole as well as for specific organ systems. Whole-body PET FDG imaging (Fig 9) illustrates the potential of biochemical imaging to map the distribution of cancer throughout the body. With the growing list of radiopharmaceutical and quantitative techniques applicable to cancer studies with PET, this field will continue to realize significant growth.

Quantification of glucose utilization in liver metastases: parametric imaging of FDG uptake with PET

Positron emission tomography (PET) fluorodeoxyglucose (FDG) studies are useful for identifying foci of increased FDG uptake in liver metastases, because of the high glycolytic rate of malignancies, as well as for monitoring changes in tumor glucose metabolism during treatment. We performed 15 kinetic PET FDG studies in four patients with metastatic liver disease. We produced parametric images of glucose metabolism in terms of the rate constant K (ml/min/g) for net phosphorylation of FDG. Tumor K values, estimated with nonlinear regression, correlated well with K values estimated with Patlak graphical analysis (r = 0.96), validating the assumption of low k4* values in liver metastases and supporting the use of pixel by pixel Patlak plot analysis of the data to generate parametric images. In normal liver, high levels of glucose-6-phosphatase produce much higher values of k4* than in liver metastases. Uncorrected Patlak graphical analysis underestimates K in normal liver, but this further increases the contrast between tumor and liver and facilitates both tumor detection and quantification. The technique is computationally feasible and is well suited for serial evaluations of tumor metabolism during treatment.

The application of positron emission tomographic imaging with fluorodeoxyglucose to the evaluation of breast disease

Positron emission tomography (PET) is a computer-aided tomographic imaging technique that uses positron-emitting compounds to trace biochemical processes of tissue, and construct images based on them. The authors applied a whole-body PET imaging technique to patients with breast masses or mammographic abnormalities using the isotope 2-[F-18]-fluoro-2-deoxy-D-glucose (FDG), in a clinical trial to evaluate the feasibility of using PET to identify primary breast cancer, axillary lymph node involvement, and systemic metastases, before surgical resection. Fourteen patients have been entered on this study, 10 of whom proved to have breast cancer. Positron emission tomography correctly predicted the nature of 12 of the 14 primary breast lesions, and correctly determined the lymph node status of 11 of the 14 patients. The authors conclude that PET with FDG has potential as a diagnostic modality for detection of primary breast cancer, particularly in the patient with radiodense breasts by conventional mammography, and that it has potential for the preoperative identification of axillary lymph node metastases.

Evaluation of the skeletal kinetics of fluorine-18-fluoride ion with PET

To evaluate the feasibility of quantitatively assessing regional skeletal fluoride uptake in humans in focal and generalized bone disease, we investigated the skeletal kinetics of [18F]fluoride ion with dynamic PET imaging. Dynamic image sets were acquired over a 60-min interval in a multiplane PET device, and input functions (plasma 18F time-activity curves) were measured directly from arterialized blood and, in some cases, determined from image-derived left ventricular cavity activity measurements. Our results indicate: 1. A steady-state ratio of [18F]fluoride ion concentration in plasma to whole blood greater than unity (1.23 for plasma to directly assayed whole blood and 1.44 for plasma to left ventricular cavity imaged concentrations. This concentration difference produces a scaling factor that must be considered when using image derived or directly measured input functions. 2. The preferred tracer kinetic model configuration for [18F]fluoride ion skeletal kinetics is a three compartment model that includes a "bound" and "unbound" bone [18F]fluoride ion compartment. 3. The rate constant for forward transport of [18F]fluoride ion from plasma to the extravascular space of bone (K1) and the regional blood volume parameter generate estimates of bone blood flow and vascular volume, respectively, that are in the physiologic range of reported for mammals. Estimates of the uptake constant for fluoride in bone, using nonlinear regression (KNLR = 0.0360 +/- 0.0064 ml/min/ml), are in very good agreement with an estimate of the same parameter obtained with Patlak graphical analysis (KPAT = 0.0355 +/- 0.0061 ml/min/ml). 4. Generating parametric images of KPAT facilitates quantification of regional bone [18F]fluoride ion kinetics. The method is computationally practical, and, with either the parametric imaging approach or with standard region of interest analysis, can be used to generate quantitative estimates of fluoride uptake (a "bone metabolic index") in focal skeletal regions or in more generalized distributions.

Structural analysis of a mouse mammary tumor virus superantigen

It has recently been shown that the minor lymphocyte stimulating-like products expressed by some mice are actually encoded by open reading frames in the 3' long terminal repeats of mouse mammary tumor viruses. These products act as viral superantigens (vSAGs). That is, they stimulate most T cells bearing particular V beta s almost regardless of the rest of the variable components of the T cell receptors expressed by those cells. To find out more about the structure of these vSAGs, a set of truncated vSAG genes was used in transfection and in vitro translation experiments to show that the functional vSAG is a type II integral membrane protein with a large glycosylated extracellular COOH-terminal domain and a small, nonessential, intracellular NH2-terminal cytoplasmic domain. These results are consistent with the fact that the vSAGs must be expressed on the cell surface in order to interact with T cells and class II major histocompatibility complex proteins. They also account for the finding that much of the V beta specificity of the vSAGs is controlled by amino acids at the COOH-terminal end of the vSAG proteins, amino acids that will be extracellular in type II proteins.

The open reading frames in the 3' long terminal repeats of several mouse mammary tumor virus integrants encode V beta 3-specific superantigens

Mice expressing the minor lymphocyte stimulation antigens, Mls-1a, -2a, or -3a, singly on the B10.BR background have been generated. Mls phenotypes correlate with the integration of mouse mammary tumor viruses (MTV) in the mouse genome. The open reading frames within the 3' long terminal repeats of the integrated MTVs 1, 3, 6, and 13 encode V beta 3-specific superantigens. Sequence data for these viral superantigens is presented, indicating that it is the COOH-terminal portion of the viral superantigen that interacts with the T cell receptor V beta element.

Transforming growth factor alpha induces collagen degradation and cell migration in differentiating human epidermal raft cultures

When cultured on plastic and treated with transforming growth factor alpha (TGF alpha), human keratinocytes exhibit an increase in proliferation at the colony periphery, apparently as a consequence of enhanced cell migration (Barrandon and Green, 1987). To investigate the effects of TGF alpha on a differentiating stratified squamous epithelium and to begin to examine the molecular basis mediating this influence, we cultured human epidermal cells on a gelled lattice of collagen and fibroblasts, floating on the air-liquid interface. Under these conditions, raft cultures differentiate and exhibit morphological and biochemical features of human skin in vivo (Asselineau et al., 1986; Kopan et al., 1987). When 3-wk-old raft cultures were treated with TGF alpha, basal cells showed a marked increase in cell proliferation. At elevated concentrations of TGF alpha, the organization of cells within the artificial tissue changed and islands of basal cells entered the collagen matrix. Biochemical analysis of the response revealed that type I collagenase and gelatinase were induced by keratinocytes within 12 h after TGF alpha treatment. In contrast, invasion of basal cells into the collagen matrix was not significant until 48-72 h post-treatment, suggesting that collagenase and gelatinase production may be a prerequisite to this phenomenon. These results have important implications for the possible role of TGF alpha in squamous cell carcinoma and tumor invasion.

Parametric images of myocardial metabolic rate of glucose generated from dynamic cardiac PET and 2-[18F]fluoro-2-deoxy-d-glucose studies

We describe a method for generating parametric images of the myocardial metabolic rate of glucose (MMRGlc) with positron emission tomography (PET). The method employs serially acquired images of 2-[18F]fluoro-2-deoxy-D-glucose (FDG) uptake and a Patlak graphical analysis of the image data. The arterial input function is derived from images of the left ventricular blood pool calibrated with 18F-plasma measurements. The approach is computationally fast enough to be used in a clinical environment. The MMRGlc parametric images improve myocardial contrast relative to non-parametric images, especially in studies with poor myocardial uptake of FDG. In addition, MMRGlc parametric images consolidate the large amount of data in a dynamic PET study into a clinically usable image set.

A superantigen encoded in the open reading frame of the 3' long terminal repeat of mouse mammary tumour virus

Mice express a collection of superantigens, which bind to class II major histocompatibility proteins and interact with T cells bearing particular V beta chains as part of their alpha beta receptors. These superantigens have been suggested to be encoded by exogenous or endogenous mouse mammary tumour viruses. One such superantigen is now shown to be encoded in the open reading frame of the long terminal repeat of a mammary tumour virus, a gene of previously unknown function.

Negative regulation in correct tissue-specific expression of mouse mammary tumor virus in transgenic mice

Mouse mammary tumor virus (MMTV) is an endogenous murine retrovirus that is expressed in the epithelial cells of the mammary and salivary glands, lungs, kidneys, and seminal vesicles and in the lymphoid cells of the spleen and thymus. Several studies have shown that the long terminal repeat (LTR) of this virus can direct the expression of reporter genes to the same tissues in transgenic mice. To determine whether multiple regulatory elements within the LTR are involved in this tissue-specific expression, we have established lines of transgenic mice containing transgenes that have deletions in the MMTV LTR. Deletions of all LTR sequences upstream of -364 or of LTR sequences from -165 to -665 both result in the expression of linked reporter genes such as the simian virus 40 early region or the bacterial enzyme chloramphenicol acetyltransferase in novel sites, such as the heart, brain, and skeletal muscle; expression of endogenous MMTV and transgenes containing the full-length LTR is not detected in these organs. Negative regulation appears to involve more than one region, since deletion of sequences between either -201 and -471 or -201 and -344, as well as sequences upstream of -364, results in inappropriate expression in heart, brain, and skeletal muscle. Therefore, a negative regulatory element(s) in the MMTV LTR can suppress transcription from the viral promoter in several different organs. This represents the first example of generalized negative regulatory elements that act in many different tissues in transgenic mice to prevent inappropriate expression of a gene.

TGF-beta and retinoic acid: regulators of growth and modifiers of differentiation in human epidermal cells

In the epidermis of skin, a fine balance exists between proliferating progenitor cells and terminally differentiating cells. We examined the effects of TGF-beta s and retinoic acid (RA) on controlling this balance in normal and malignant human epidermal keratinocytes cultured under conditions where most morphological and biochemical features of epidermis in vivo are retained. Our results revealed marked and pleiotropic effects of both TGF-beta and RA on keratinocytes. In contrast to retinoids, TGF-beta s acted on mitotically active basal cells to retard cell proliferation. Although withdrawal from the cell cycle is a necessary prerequisite for commitment to terminal differentiation, TGF-beta s inhibited normal keratinization in suprabasal cells and promoted the type of differentiation commonly associated with wound-healing and epidermal hyperproliferation. The actions of TGF-beta s and RA on normal keratinization were synergistic, whereas those on abnormal differentiation associated with hyperproliferation were antagonistic. These observations underscore the notion that environmental changes can act separately on proliferating and differentiating cells within the population. Under the conditions used here, the action of TGF-beta s on human keratinocytes was dominant over RA, and TGF-beta s did not seem to be induced as a consequence of RA treatment. This finding is consistent with the fact that RA accelerated, rather than inhibited, proliferation in raft cultures. Collectively, our data suggest that the effects of both factors on epidermal growth and differentiation are multifaceted and the extent to which their action is coupled in keratinocytes may vary under different conditions and/or in different species.

Selective expansion of T cells expressing V beta 2 in toxic shock syndrome

Infection with Staphylococcus aureus and the production of toxic shock syndrome toxin-1 (TSST-1) have been implicated in the pathogenesis of toxic shock syndrome. Previous in vitro studies have demonstrated that TSST-1 is a powerful but selective stimulator of human T cells, and that the majority of activated cells express the TCR V beta 2 gene segment. We therefore studied patients with toxic shock syndrome using a modification of the PCR to determine if expansion of V beta 2+ T cells is a marker of the in vivo disease process. Five of eight patients studied demonstrated markedly elevated levels of circulating V beta 2+ T cells, whereas none showed significantly elevated levels of T cells expressing other V beta gene segments. The results suggest that toxin-mediated T cell activation, which involves a large fraction of the human T cell repertoire, may be critical in the pathogenesis of this disease.

Abnormalities of glomerular basement membrane in acute postinfectious glomerulonephritis

The segmental abnormalities of glomerular basement membrane (GBM) were studied by electron microscopy in 69 renal biopsies with acute postinfectious glomerulonephritis (APGN) and correlated with the general morphologic features and clinical findings. Thirty-six were children and 33 were adults. Biopsies were grouped into three stages by light microscopy: exudative stage (25 patients), exudative-proliferative stage (26) and proliferative stage (18). Subepithelial deposits or "humps" were present in 59 patients (86%). The frequency of humps was significantly lower at the proliferative stage than that noted in the earlier biopsies (p less than 0.01). Intramembranous, subendothelial and mesangial deposits were shown in 83% to 88% of the patients. The overall frequency of GBM abnormalities was 45%, showing significantly higher frequency in children than in adults (p less than 0.01). Dissolving subepithelial deposits were often present in the foci with GBM abnormalities. The GBM lesions were not related to more severe clinical manifestations or outcomes, but tended to occur more frequently in later biopsies (p less than 0.01). These results suggest that abnormalities of GBM in APGN are more often present than formerly assumed, especially in children, and could be a normal response to subepithelial deposits. The occurrence of these lesions in other types of immune-related glomerulonephritis may be considered along the same lines.

V beta-specific stimulation of human T cells by staphylococcal toxins

The staphylococcal toxins are responsible for a number of diseases in man and other animals. Many of them have also long been known to be powerful T cell stimulants. They do not, however, stimulate all T cells. On the contrary, each toxin reacts with human T cells bearing particular V beta sequences as part of their receptors for major histocompatibility complex protein-associated antigen. The specificity of these toxins for V beta s puts them in the recently described class of superantigens and may account for the differential sensitivity of different individuals to the toxic effects of these proteins.

Ultrastructural changes in IgA nephropathy in relation to histologic and clinical data

In order to evaluate the ultrastructural changes in IgA nephropathy (IgAN) and their relationship with light microscopic and clinical features, renal biopsy material from 239 Korean patients with IgAN was studied by light, electron and immunofluorescence microscopy. Forty-one were children and 198 were adults. Modified classification of Meadow et al (1972) for Henoch-Schönlein nephritis was used for the histologic grading of glomerular lesions. Forty-three adults (18%) exhibited histologic grades IV and V lesions in association with more severe clinical findings, when compared to the remaining 196 patients with histologic grades I to III. A significant difference was noted between children and adults in the severity of the glomerular lesions (P less than 0.01). Mesangial deposits were observed in all (100%), subendothelial deposits in 37%, subepithelial deposits in 18%, abnormalities in glomerular basement membrane (GBM) in 20%, mesangiolysis in 44%, and mesangial interposition in 25%. The frequency of GBM abnormalities and subepithelial deposits in children was significantly higher than that seen in adults (P less than 0.01). The abnormalities of GBM were not related to more severe clinical manifestations when our analysis was restricted to grade III histologic lesions. All of the above ultrastructural changes except for mesangial deposits were associated with more severe histologic grading in adults (P less than 0.025 or P less than 0.01). Yet a correlation between these ultrastructural changes and histologic grading could not be studied in children due to confinement of their histology within a more benign group. These results suggest that the five ultrastructural parameters described here appear to bear important prognostic value in adults with IgAN.(ABSTRACT TRUNCATED AT 250 WORDS)

A renal biopsy study of hepatitis B virus-associated nephropathy in Korea

The pathogenic role of the hepatitis B virus (HBV) infection for glomerulonephritis (GN) is not clear. The frequency of HBsAg has been studied in sera of 732 consecutive patients who have glomerular diseases by using radioimmunoassay. The frequency of HBs antigenemia was 11.9%, which was not different from that in the general population of South Korea. Of the 87 HBsAg seropositive patients with GN, 29 cases with membranoproliferative GN (MPGN) and eighteen with membranous nephropathy (MN) were diagnosed as having HBV-associated nephropathy. Eighty-seven and one-half percent of the adults with MPGN and 80% of the children with MN were HBsAg carries. The morphologic findings and laboratory data in cases with HBV-associated MPGN and MN did not differ significantly from those observed in patients with MPGN and MN without circulating HBsAg. Yet mesangial deposits were more frequently noted in patients with HBV-associated MN when compared to others with idiopathic MN. Glomerular deposits of HBsAg were not detected using indirect immunofluorescence technique. Even though HBsAg was not demonstrable within the glomeruli, HBV infection seems to play an important role in the pathogenesis of MPGN in Korean adults and MN in children.