Phosphorylation of bovine adrenal chromaffin cell tyrosine hydroxylase. Temporal correlation of acetylcholine's effect on site phosphorylation, enzyme activation, and catecholamine synthesis

Tryptic peptide fragments of tyrosine hydroxylase isolated from 32PO4-prelabeled bovine adrenal chromaffin cells are resolved into seven phosphopeptides by reverse phase-high performance liquid chromatography. All seven of the peptides are phosphorylated on serine residues. Three of these putative phosphorylation sites, peptides 3, 5, and 6, are rapidly phosphorylated (5-fold in 15 s) by both acetylcholine stimulation and potassium depolarization of the cells, and this phosphorylation is accompanied by a similarly rapid activation of the enzyme. Both phosphorylation and activation are transient and do not account for the prolonged increase in catecholamine biosynthesis produced by these stimuli. Peptides 4 and 7 show a much slower and sustained increase in phosphorylation (3-fold in 4 min) in response to acetylcholine and potassium. Phosphorylation of these peptides correlates with the sustained increase in catecholamine biosynthesis rather than enzyme activation. Peptides 1 and 2 are not stimulated by any agonist yet employed and thus show no relation to enzyme activation or catecholamine biosynthesis. Phosphorylation of all five peptides by acetylcholine or potassium is calcium-dependent. In contrast to the stimulation of phosphorylation of tyrosine hydroxylase on multiple sites, forskolin stimulates the phosphorylation of only peptide 6, and this is accompanied by a coordinated activation of tyrosine hydroxylase and increased catecholamine biosynthesis. These findings show that the phosphorylation of tyrosine hydroxylase in intact cells is more complex than predicted from in vitro results, that at least two protein kinases are involved in the secretagogue-induced phosphorylation of tyrosine hydroxylase, and that the regulation of catecholamine biosynthesis, in response to phosphorylation, appears to involve both tyrosine hydroxylase activation and other mechanisms.

Outpatient rehabilitative training in patients with cardiovascular disease: emphasis on training method

As our ability to evaluate cardiovascular patients expands and direct oxygen consumption measurements are available, exercise prescriptions can be better individualized for each patient. By using basic principles of frequency and duration and specifically basing intensity and progression on percent of maximum oxygen consumption, protocols using various modes of exercise may be defined so that each patient entering cardiovascular training programs will gradually progress. This methodology discussion presents concise progressions for both phase II monitored and phase II nonmonitored medically supervised exercise training. The phase II monitored protocol consists of levels 1 through 6 and is designed to be completed within a minimum of six 1-hour sessions. The phase II nonmonitored protocol consists of levels 7 through 12 and is designed to be completed within 12 weeks. The ultimate goal is for each patient to safely progress to a training level that can be maintained safely and effectively by the patient. A total of 192 patients enrolled in our phase II programs have safely completed both components and are in long-term maintenance programs.

Exercise testing in patients with musculoskeletal handicaps

To determine safe and effective exercise testing techniques for musculoskeletally handicapped individuals, 20 patients (mean age, 61 years) were studied. Types of handicaps included various degrees of paralysis of arms and legs, and leg amputations. Seventeen of the 20 patients had concurrent cardiovascular problems. All were currently hospitalized, engaged in various physical therapy exercises, and referred for exercise testing to increase rehabilitation therapy or for cardiovascular evaluation. Of 20 tests, arm ergometry was used in 15, leg or combination arm-leg ergometry in four, and treadmill in one. All patients completed testing with mean increases in heart rate (82 to 106 bpm arm, 88 to 125 other) and systolic blood pressure (114 to 127 mmHg arm, 118 to 146 other). Low-grade atrial and ventricular ectopy occurred in eight patients, decrease or plateauing of systolic blood pressure in three, increased diastolic blood pressure in two, and significant (greater than or equal to 1mm) ECG S-T segment displacement in one. With the use of appropriate equipment for each patient, exercise testing can be done safely and effectively in musculoskeletally handicapped individuals.

Micro-angiopathic haemolytic anaemia and an unusual lactate dehydrogenase iso-enzyme pattern in metastatic adenocarcinoma. A case report

Micro-angiopathic haemolytic anaemia is an unusual but well-recognized complication of metastatic adenocarcinoma. A young black man presented with red cell fragmentation, compensated disseminated intravascular coagulation and leuco-erythroblastosis. Metastatic adenocarcinoma of the stomach was suspected but only demonstrated at autopsy. An unusual finding was the elevation of the slow-moving lactate dehydrogenase iso-enzyme (LDH5) level in the plasma which was shown to be produced by metastatic tumour cells recovered from the bone marrow.

Studies on cultured fibroblasts in a case of methylmalonic aciduria

A case of methylmalonic aciduria is described. The clinical course was unusually mild, the child surviving to the age of 8 years. Studies on cultured fibroblasts confirmed a defect in propionate metabolism which was non-responsive to hydroxycobalamin in vitro. Polyethylene-glycol-induced cell fusion with a known methylmalonyl co-enzyme apomutase-deficient cell line showed genetic complementation indicating that in this patient the defect was in one of the enzymes required for 5-deoxyadenosyl cobalamin synthesis.

Inheritance of functional foreign genes in plants

Morphologically normal plants were regenerated from Nicotiana plumbaginifolia cells transformed with an Agrobacterium tumefaciens strain containing a tumor-inducing plasmid with a chimeric gene for kanamycin resistance. The presence of the chimeric gene in regenerated plants was demonstrated by Southern hybridization analysis, and its expression in plant tissues was confirmed by the ability of leaf segments to form callus on media containing kanamycin at concentrations that were normally inhibitory. Progeny derived from several transformed plants inherited the foreign gene in a Mendelian manner.

Identification of nerve growth factor receptors in primary cultures of chick neural crest cells

Primary cultures of chick neural crest cells obtained from explanted neural tubes have binding sites for radioiodinated nerve growth factor ([125I]NGF) but not for radioiodinated epidermal growth factor ([125I]EGF). The binding of [125I]NGF was shown to be a specific and saturable process with a high affinity (Kd = 0.3 nM) for the ligand. Despite the expression of these NGF binding sites, incubation of the neural crest cultures with nerve growth factor did not induce neurite outgrowth; no morphological alterations were observed. This was not due to an inability of the cells to express a neuronal phenotype, since the neural crest cells spontaneously differentiated into neurite-bearing cells. However, the nerve growth factor binding sites do appear to be functional receptors, since nerve growth factor could produce a modest induction of ornithine decarboxylase. The quantity of nerve growth factor binding sites seemed to be independent of the phenotype expressed by the neural crest cells, since both pigmented cells and neuron-like neural crest cells exhibited binding. These findings suggest that the differentiation of neural crest cells into mature nerve growth factor-responsive neurons may involve the coupling of nerve growth factor receptors to cellular responses important in the expression of the neuronal phenotype.

Coeliac disease. Reappraisal of clinical diagnosis

Twelve children previously diagnosed as having coeliac disease on criteria now regarded as incomplete have been reinvestigated. Six were found to have an intestinal mucosal lesion characteristic of coeliac disease. All but one had been asymptomatic on a normal diet for more than 18 months. Response to diet fails to distinguish between coeliacs and non-coeliacs. Establishing the diagnosis of coeliac disease by intestinal biopsy is essential, since even apparently symptomless individuals are at considerable risk.

Peripheral gangrene in infancy and childhood

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