Conservation of receptor antagonist anti-tumor activity by epidermal growth factor receptor antibody expressed in transgenic corn seed

Recombinant protein production in plants such as corn is a promising means to generate high product yields at low comparable production cost. The anti-EGFR monoclonal antibody C225, cetuximab, is a well-characterized receptor antagonist antibody recently approved for the treatment of refractory colorectal cancer. We initiated a study to test and compare the functional activity of glycosylated and aglycosylated C225 produced in stable transgenic corn seed. Both corn antibodies were shown to be functionally indistinguishable from mammalian-derived C225 in demonstrating high-affinity binding to the EGF receptor, blocking of ligand-dependent signaling, and inhibiting cell proliferation. In addition, consistent with cetuximab, both corn antibodies possessed strong anti-tumor activity in vivo. Acute dose primate pharmacokinetic studies, however, revealed a marked increase in clearance for the glycosylated corn antibody, while the aglycosylated antibody possessed in vivo kinetics similar to cetuximab. This experimentation established that corn-derived receptor blocking monoclonal antibodies possess comparable efficacy to mammalian cell culture-derived antibody, and offer a cost effective alternative to large-scale mammalian cell culture production.     

Smoking and Drinking Behavior in Patients with Head and Neck Cancer: Effects of Behavioral Self-Blame and Perceived Control

Patients who continue to use tobacco or alcohol following treatment for head and neck cancers are at greater risk for cancer recurrence and mortality. The present study examined the effects of behavioral self-blame and perceived control over health on smoking and alcohol use in a sample of 55 patients with cancers of the head and neck. Measures of self-blame, perceived control, and depression were administered and an assessment of past and current smoking and drinking behavior was obtained. As anticipated, continued smoking after completion of oncologic treatment was predicted by the interaction of behavior specific self-blame and perceived control. Patients who attributed the cause of their cancer to their past substance use exhibited a lower likelihood of smoking only if they also held the expectancy that their future cancer-related health was contingent on their own behavior. Among patients not holding the belief that cancer recurrence was contingent on their own actions, self-blame was associated with a higher probability of continued smoking. Self-blame and perceived control had no effect on continued alcohol use.     

Developments in cardiovascular ultrasound. Part 2: Arterial applications

Many of the changes resulting from arterial disease can be measured, using Doppler ultrasound for measurement of blood velocity and B-scan imaging for measurement of tissue structure and composition. Wall thickness, the degree of arterial narrowing and plaque volume can be measured using B-scan imaging, and 3D ultrasound can be used to improve the accuracy of measurements of plaque volume and for improved visualisation of complex arterial geometries. Measurement of the dynamic properties of the arterial wall permits estimation of wall elasticity and plaque motion. From the Doppler signal, measurements of blood velocity are used to estimate the degree of arterial narrowing and volumetric flow, although measurement errors can be large. Wall shear stress can be estimated by measuring the velocity gradient at the vessel wall. The problems of inadequate spatial resolution and interference from overlying tissue are largely removed when intravascular systems are used, and these have superior capability in the assessment of arterial structure and tissue composition. However, measurement of quantities relating to blood flow is more difficult using the intravascular approach, as the indwelling cather disturbs the blood flow pattern, and currently, assessment of flow and vessel cross-section are not performed at the same site.     

Histologic diagnosis of Hirschsprung's disease. The value of concurrent hematoxylin and eosin and cholinesterase staining of rectal biopsies

False positive and negative results can complicate the diagnosis of Hirschsprung's disease (HD) with the acetylcholinesterase (AChE) stain. To improve the diagnostic value of this test, the authors evaluated the concurrent hematoxylin and eosin (H and E) staining of extra sections after the AChE procedure. Flash-frozen (FF), cryostat-cut (CC) sections of rectal suction biopsies from 96 patients with constipation were evaluated by AChE together with H and E staining of additional unstained sections. In 13 of 15 cases of HD with a diagnostic (positive-A) AChE pattern, the H and E sections confirmed the diagnosis. In five cases with other AChE patterns, the H and E sections were instrumental when the diagnosis was made. Of the 76 non-HD subjects with positive-B (n = 8), equivocal (n = 6), and negative (n = 62) AChE patterns, the H and E sections eliminated the diagnosis in 62 (81%). Neuronal and nerve fiber morphologic characteristics were excellent. Rebiopsies were needed in 14 subjects (19%) when there was failure in finding neurons. Simplicity, quickness, and the high quality of the histologic preparations make this procedure a useful adjunct to the AChE stain.     

Pulmonary artery angiosarcoma: a clinicopathologic and radiological correlation

A 69-year-old man presented with cough, shortness of breath, and fatigue. He was initially treated for allergies and then for pulmonary embolism. Radiologically, a tumor mass was found to occlude the right pulmonary artery and involve the pulmonary trunk. A right pneumonectomy was performed. Histologically, a cellular malignant spindle and epithelioid tumor with areas of necrosis and brisk mitotic activity was seen. In some areas, the tumor appeared to form vascular channels. Focal osteosarcomatous differentiation was present. Immunohistochemical studies were performed including vimentin, smooth muscle actin, desmin, CD31, CD34, S100, and pan-cytokeratin. The tumor cells were positive for CD31 and vimentin and negative for pan-cytokeratin, CD34, and S100. Two months after surgery, the patient was alive and well.     

An in vitro study of a microbubble contrast agent using a clinical ultrasound imaging system

Optimal insonation settings for contrast imaging are yet to be specified, mainly due to the lack of good understanding of the behaviour of the microbubbles. A satisfactory model that explains the behaviour of individual contrast agent scatterers has not yet been reported in the literature. An in vitro system based on a commercial scanner (ATL HDI3000) has been developed to investigate the backscatter of such agents. Suspensions of Definity were introduced in an anechoic tank. The frequency of transmitted ultrasound varied from 1 to 5 MHz, pulse period from 2 to 10 periods and peak negative acoustic pressure from 0.08 to 1.7 MPa. The backscatter at the fundamental and second harmonic frequency windows from the agent was normalized in terms of the corresponding components of backscatter from a blood mimicking fluid suspension. The agent provided a dominant resonance effect at 1.6 MHz transmit frequency. Second harmonic normalized backscatter averaged around 9 dB higher than the fundamental. The normalized fundamental backscatter intensity was linear with peak negative pressure. The second harmonic at resonance peaked at 0.5 MPa suggestive of bubble disruption above such pressure. The system proved capable of illustrating the ultrasonic behaviour of Definity in vitro, and the investigation suggested particular insonation conditions for optimal image enhancement using Definity.     

Lymphocyte transformation responses to phytohaemagglutinin and pokeweed mitogen in patients at differing stages of HIV infection: are they worth measuring?

AIMS--To determine whether the routine measurement of lymphocyte transformation responses to mitogenic stimuli provide any information additional to that available from routine T cell CD4 and CD8 analysis in patients with HIV infection. METHODS--The case records of 197 immunologically investigated HIV seropositive patients were reviewed. The influence of disease stage on T lymphocyte subsets and lymphocyte transformation responses (LyTR) to phytohaemagglutinin (PHA) and Pokeweed mitogen was assessed. RESULTS--The median CD3 and CD4 counts and LyTR to PHA and Pokeweed mitogen were highest in patients with persistent generalised lymphadenopathy (PGL) and decreased progressively in the order: asymptomatic patients, those with ARC, those with AIDS. LyTR to PHA was preserved in over 70% of all patients, but the response to Pokeweed mitogen was depressed in 8% of patients with PGL, 34% of asymptomatic patients, 68% of those with ARC and 78% of those with AIDS. Subnormal values of both CD4 + T cells and LyTR to Pokeweed mitogen were more common in patients with ARC and AIDS (68%) than in those who were asymptomatic or had PGL (20%). CONCLUSIONS--CD4 T cell analysis and LyTR to Pokeweed mitogen, but not to PHA, both correlate with disease states in patients with HIV infection.     

Limited nerve impulse blockade by "leashed" local anesthetics

To measure the depth of the local anesthetic binding site within the neuronal membrane, biotin-containing polyethylene glycols having zero, three, and six ethylene glycol subunits were added to the p-amino termini of tetracaine and procaine, thereby interposing a pharmacologically inert "spacer" molecule between the local anesthetic and the biotin moiety. These biotinyl-local anesthetic derivatives produced "tonic" inhibition of the compound action potential of split, desheathed frog sciatic nerves in a concentration-dependent, reversible manner. However, no inhibition of the action potential occurred when sufficient avidin, a 66,000-MW protein that binds four biotins, was present to bind and anchor the biotin-containing end of each derivative outside the plasma membrane. Increasing the "leashed" anesthetic derivative's concentration to 4 times that which reduced impulse height by 50% in the absence of avidin still produced no detectable block when equimolar avidin was present. Apparently, the "spacer" in the derivative compound was too short to permit the avidin-complexed anesthetic to reach its site of action on the sodium channel. In a similar fashion, the local anesthetic derivatives produced "use-dependent" block when drug-treated nerves were stimulated at 40 Hz in the absence of equimolar avidin, but failed to produce "use-dependent" block when equimolar avidin was present. In common with others, we assume that tertiary amine local anesthetics may reach their binding site via hydrophobic (transmembrane) pathways without necessarily entering the cytoplasm. Thus, since our longest local anesthetic derivative, that containing six ethylene glycol subunits, placed the local anesthetic group a maximum of 15-18 A from the surface of the avidin moiety, we conclude that the local anesthetic binding site for block of sodium channels of amphibian nerve must be greater than or equal to 15 A from the outer surface of the plasma membrane.     

Paramagnetic macrocyclic complexes as contrast agents for MR imaging: proton nuclear relaxation rate enhancement in aqueous solution and in rat tissues

Paramagnetic macrocyclic chelates show promise as magnetic resonance (MR) imaging contrast agents due to stability and relaxivity comparable to those of DTPA-type chelates. For the three copper and manganese macrocyclic complexes studied in aqueous solution, T1 and T2 relaxivities ranged from 0.14 to 5.88 mM-1sec-1 at 6.25 MHz. In rats, the intravenous administration of 16 mumol/kg of Mn(cyclam) caused the liver T1 relaxation rate to double at 15 minutes after injection. T1 measurements by pulsed MR imaging and manganese analyses on excised tissue showed that both relaxation rate (1/T1) and manganese content of liver and kidney increase linearly with the dosage of Mn(cyclam). The linear relationship between 1/T1 and manganese content can be considered an "in tissue" relaxivity plot for the agent. The resulting relaxivity is 54 mM-1sec-1 in liver, compared with 3.1 mM-1sec-1 in aqueous solution. Although this work is preliminary, the implication for medical MR imaging applications is that macrocyclic contrast agents can be effective at approximately one-tenth the current typical dose used for gadolinium DTPA.