Plant physiology: the ups and downs of guard cell signalling.

How is specificity encoded in calcium-based signal transduction systems? Recent evidence shows that oscillations in the cytosolic free calcium concentration of guard cells are necessary for stimulus-specific stomatal closure in plants.

Calcium oscillations in higher plants.

There is considerable interest in the possibility that stimulus-induced oscillations in cytosolic free calcium encode information that is used to specify the outcome of the final response in calcium-based signalling pathways in plants. Recent results provide conclusive evidence that plant cells can decipher complex calcium signatures.

Progressive morphological abnormalities observed in rat spinal motor neurons at extended intervals after axonal regeneration.

It is generally accepted that mammalian spinal motor neurons return to normal after axotomy if their regenerated axons successfully reinnervate appropriate peripheral targets. However, morphological abnormalities, recently observed in spinal motor neurons examined 1 year after nerve crush injury, raise the possibility that delayed perikaryal changes occur after regeneration is complete. In order to distinguish between chronic and progressive alterations in neurons with long-term regenerated axons, rat spinal motor neurons and dorsal root ganglion cells were examined at 5 and 10 months following unilateral sciatic nerve crush. Neurons with regenerated axons were identified by retrograde labelling with horseradish peroxidase. The structural properties of neurons ipsilateral to nerve injury were compared to those of neurons from the spinal cord and dorsal root ganglia on the contralateral side and from age-matched control rats. At 5 months postcrush, the morphology of motor and sensory neurons ipsilateral to injury was comparable to that of control cells. However, several features of the motor neurons with regenerated axons distinguished them from control motor neurons at 10 months postcrush. Mean perikaryal area of ipsilateral spinal motor neurons was larger than the means for control motor neurons (p less than .001). Ipsilateral spinal motor neurons also appeared clustered within the spinal cord and had thicker dendrites. Dorsal root ganglion cells with regenerated axons were slightly larger than control cells at 10 months postcrush but they exhibited no other morphological changes. The present findings indicate that spinal motor neurons are progressively altered after their regenerated axons have reestablished functional synapses with their peripheral targets.

Gamma probe assisted ex vivo detection of small lymph node metastases following the administration of indium-111-labeled monoclonal antibodies to colorectal cancers.

This study evaluated the ability of ex vivo gamma-probe scanning to detect lymph node metastases in resected surgical specimens from primary colorectal carcinoma patients undergoing external scintigraphy following intravenous administration of 4.1-5.3 mCi of 111In-labeled anti CEA monoclonal antibodies. The ex vivo probe counting technique led to a twofold to fourfold increase in the number of detectable lymph nodes with the majority measuring 2-5 mm in diameter. Results indicate a potentially useful role for ex vivo probe counting in detection and mapping small (2-5 mm) lymph nodes metastases.

Safety and role of repeated administrations of Indium-111-labeled anti-carcinoembryonic antigen monoclonal antibody ZCE 025 in the postoperative follow-up of colorectal carcinoma patients.

The safety and clinical utility of repeated administrations of 111In-ZCE 025 were evaluated in 25 patients who have undergone colorectal carcinoma resection. Fifteen patients were clinically and radiologically free of recurrences and asymptomatic while 10 had rising CEA and/or symptoms. We repeatedly imaged the patients following intravenous administrations of 40 mg ZCE 025, every 4 to 6 mo. Side effects occurred in 16% of patients who received two or more infusions. Sixteen lesions were detected by immunoscintigraphy in 11 patients who were free of disease by CT scans or other imaging modalities. Ten recurrences were surgically confirmed in seven patients. Radiographic and clinical follow-up confirmed the remaining 6 Mab-positive lesions. Elevated human anti-mouse antibody (HAMA) titers were detectable in the sera of 30% and 64% of patients following the 1st and 2nd Mab injection respectively, but did not interfere with successful immunoscintigraphy nor correlated with the occurrence of side effects. This study suggests that a negative Mab scan indicates that a patient will remain free of recurrence; conversely, a positive scan was associated with recurrences of disease.

Functional properties and nodal spacing of myelinated fibers in developing rat mental and sural nerves.

While the postnatal length growth of the largest internodes in the rat sural nerve (SN) is proportional to nerve elongation, in the developing inferior alveolar nerve (IAN), early postnatal myelin sheath remodelling allows internodal lengthening to exceed the growth rate of the whole nerve. To assess the functional consequences of ongoing myelin sheath remodelling in a developing nerve, we examined the physiological properties of the mental nerve (MN), a cutaneous IAN branch and the SN during maturation. In addition, the nodal spacing and the microscopic anatomy of the nodes in the two nerves were studied. The youngest MNs and SNs (2 weeks) exhibited comparable sensitivities to K(+)-channel blockade with 4-aminopyridine (4-AP), although myelin sheath remodelling was more frequent in the MNs. Subsequently, myelin sheath remodelling ceased in both nerves but the MNs exhibited a greater sensitivity to 4-AP. Large fibers in adult MNs and SNs had a similar nodal anatomy but the former had shorter internodes. Thus, myelin sheath remodeling, per se, does not appear to be a determinant of 4-AP sensitivity in mammalian myelinated fibers. Rather, sensitivity to potassium channel blockade is more likely mediated at the internodal or molecular level.

Radioimmunodetection of colorectal carcinoma with 111In-labelled monoclonal antibody IVP ZCE 025 (a tissue culture-produced anti-CEA MAb).

The aims of this prospective, nonrandomized phase I/II study were to evaluate (1) the safety and (2) the detection rate of tissue culture-derived, 111In-labelled anti-CEA monoclonal antibody IVP ZCE 025 in patients with primary, metastatic and occult colorectal carcinomas. 111In-IVP ZCE 025 imaging correctly identified 31 of 37 primary colorectal carcinomas, 10 of 19 hot liver metastases, 11 of 16 distant metastases and seven of seven local tumour recurrences. Previously unsuspected tumours were detected by IVP ZCE 025 imaging in 11 of 34 patients. The scans were also true negative in four patients. The overall performance characteristics of IVP ZCE 025 at monoclonal antibody doses of 1.0-5.0 mg were comparable to those obtained with 40.0 mg ascites-produced ZCE 025. No clinical or biochemical adverse reactions were encountered in the 61 patients entered into this study.

Methods for the estimation of the number and quality of animal cells immobilized in carbohydrate gels.

Rapid and reliable methods for the determination of survival, proliferation, and metabolic activity of immobilized cells in gels are described. The first method is based on an MTT assay that measures qualitatively and quantitatively the metabolic activity of the cells. The second method determines cell number by measuring the amount of DNA available for Feulgen staining. In the third method, two fluorescent dyes are used to differentially stain viable and dead cells. The fourth method involves the use of glutaraldehyde to protect the cells when melting the gel to facilitate hemocytometric count. The presented techniques should help to test the efficiency of the immobilization procedures and to monitor the growth and survival of immobilized cells.